Heinz,
I've spent a good bit of time off the coast of Washington in both a CD-22 and in my Tomcat. I wouldn't think about doing a long trip along our coast until about mid-July. Between mid July and mid September, you can often find good weather/seas off our coast and sometimes for many days in a row. In August, I'd estimate 3-4 days out of 5 are calm enough for C-dory travel especially in the early AM through noon +/- 2 hours. Since the sunrise is early then, that's at least 6 hours of good traveling time. In June, the coastal waters are nice more like 40% of the time and in May it's more like 25-30% of the time. Also when it's not "nice", it's not nice in a much worse way early in the season. 10+ seas are not at all uncommon off our coast in May but 6-8 are more typical.
While I'm not super familiar with the N. California coast, a quick perusal of the map suggests that there would be a few long runs between fuel stops. Once you're outside of the San Fran bay, Bodega bay is not too far. However, after that, it looks like Fort Bragg would be the next possible stop and that's about 120miles. Even in "nice" water off the coast up here, you'd be hard pressed to make better than 16kt's going N, W or NW in a CD 25 (of course it all depends on how calm the seas are but in my experience in a 22, it was the rare day in August when I could open up the throttle going any direction other than east (with the small swells/waves at my back). Winds from the NW are not uncommon. So to cross a 120 miles at 16kts is probably a full 8-10 hour day by the time you eat and take the occasional stop to look at sea life or have a potty break. After Fort Brag, it looks like another 100 or so mile run to Eureka after which the ports get a bit closer together.
Many of the ports along the way are upstream of rivers just a bit and that typically means crossing a bar. When the tide is coming in and there's a good outflow on the river, this can lead to nasty conditions to cross the bar (especially in certain wind conditions). As a result some ports may only be accessible at near slack tide. On the right days, that's not a big deal and you can plan for it or wait for the near slack tide periods. On days where the weather goes bad, making a decision to cross a bar or to hold out in bad weather can be a difficult one and that's what gets a lot of people in trouble - especially for people on a schedule.
For planning when I'm willing to take my boat offshore, I use this web site -
http://forecasts.surfingmagazine.com/ . It provides wind and swell predictions for 6-7 day out from the current day. To properly use this site, you need to select the area of interest and then look at the 3 separate maps that show wind, swell height and swell period. At the top of the map you can select which of the 3 pieces of data you wish to see. At the bottom of the map, you can select the date and time in 6 hour intervals. The 1-2 day predictions are pretty accurate, the 3-4day predictions are OK and the 5-7's are not so accurate. However, if there is a 3 day window in which conditions are predicted to be nice all three days, I can generally count on the middle of those three days to be good.
To make good use of these predictions, you have to develop a sense of what the seas will look like for various conditions. Swell height, swell period and winds all affect sea state. There's a few good rules of thumb that can give you a sense of whether the ocean will be OK. First if the swell period in seconds is 3 or more greater than the swell height in feet, it's generally manageable for swells <6-8'. For larger swells, I want to see greater differences in [period(s) - height(f)].
In low wind conditions: I have had my CD-22 in 10-12' swells that had a 18-20s period with not much wind and it was quite manageable going slow (6-8kts) perpendicular to or into the swells and I could average 12kts with them at my back (being careful to not go too fast down the front side of a swell and stuff the bow into the next one). Going into such swells I probably only made about 5-6kts. So those were OK to fish in but not so great for making distance. 3-4' swells with 6-8s periods I could do about 6-10kts going into them or perpendicular to them and 16-20kts with them at my back. 3-4' swells with 10s+ periods things start to feel pretty much like a calm lake (in light winds) and I could travel pretty much at any speed I like. On the other hand, 4' swells at a 4-5s period can be quite nasty and feel a bit like being in a washing machine.
Winds <10kts didn't generate enough wind waves to cause problems. 15kts creates enough chop to slow me down a little and 20-25kts creates wind waves that would keep my 22 traveling in the 5-12kt speed range depending on other conditions.
In the Tomcat, I can travel much faster and deal with higher winds/worse swell conditions than I ever could in the 22 but I generally use the same guidelines as I used in my 22. For me, swells bigger than 4' need to have a period thats in the 8-10s range or higher before the ocean feel calm enough to make the day enjoyable. Sure I can (and have) traveled and fished in worse conditions but at some point it's more work than fun. I like winds <15kts but will go out in 20kts when the swells are low/long period. 25kts it's time to stay in port or get into port as it likely won't be fun. My recommendation is that you try a few trips just outside the bay when the winds are light and the swells are <4' so that you can start to get a sense of what the ocean feels like at different combinations of wind, swell height and swell period. Once you start to have a mental picture of what the numbers translate into in terms of your own eyes (and you and your wife's stomachs), then you'll be in a better position to plan longer trips off shore.
Also, as Sunbeam points out, the Inside Passage is actually fairly protected for much of the way so it's usually a lot easier to handle than the coastal waters. On the Inside Passage, there are only a few stretches where you're exposed to open ocean. In particular, the brief run from Port Hardy north requires a good weather window. Much of the rest of the trip, you're in waters where the wind fetch is less than a few miles and unless the wind is from the S or SE (parallel to many of the channels), the waves don't build very high. That's not to say that the weather can't be nasty in the Inside Passage but rather to say that the weather has to be fairly nasty locally to generate bad boating conditions. In contrast, on the ocean, the long fetch means that bad weather 1000+ miles away can generate nasty local conditions.
If you want to get practice for an Inside Passage trip, I'd suggest that you start by cruising Puget Sound from say Olympia to Friday Harbor. The conditions in the sound are more similar to what you would encounter on an Inside Passage trip with the exception of more civilization and lower tidal exchanges. After I tried that, I'd take a cruise or two along the east side of Vancouver island and check out some of the fjords on the mainland side. The conditions there are even closer to what you will see on the inside passage and the amount of civilization drops as you head north or run up the fjords. Then I'd plan for the longer Inside passage trip.
After saying all of the above, I don't want to discourage you from going into the ocean in your 25. It's very doable in the right weather. I know multiple C-Brats who have traveled plenty in the Puget Sound or the Strait of Juan de Fuca that are afraid to go out into the ocean. I also know that many of them have been in nastier conditions in the Strait of Juan de Fuca than what they would encounter on a typical August day on the ocean. In fact the Strait is usually worse than the ocean in August as it tends to funnel wind. Yet, these particular brats are afraid of the ocean. It's mostly because they haven't done it so the unknown is scary to them. Once you do it a few times it get's less scary. Once you've done dozens of times, you get some decent understanding of what the swell/wind numbers mean in practice and once you've done it a 100+ times you get to where you're not worried about it. Not because you're over confident but because you've been over confident a few times before and now know enough to not put yourself out in the ocean when conditions have a good chance of turning on you. E.g. you keep a healthy level of fear but you manage the risk appropriately. So I say give it a try. Stick you're toe in the water so to speak. However, planning a trip from SF to the Friday Harbor on the water for your first big ocean cruise is more like jumping in the deep end than sticking your toe in the water. So start out with shorter trips and build up to it.