Hi
bizzylizzy - Welcome to FlyerTalk!
Well it sounds like you guys need a vacation, so let's see if we can help you have a great one. Not taking one at all doesn't sound like the right path, now does it?
Some things come to mind as I read through your post:
*What is the itinerary that Trailfinders would offer you? Would you primarily be choosing that option because you wouldn't have to plan an itinerary (or because you got a great bargain, or because they would worry about the details, or what?) California is physically large and also has a great diversity in what visitors can do here. That means that you may be on itinerary out of simplicity in planning, but then you are disappointed to experience a trip that has you moving around more than you'd like and seeing things you don't want to see.
*Would you and Mr. bizzylizzy rather stay in one place longer? Or does changing hotels and locations every other day or so sound good to you?
*What's your preference across big cities, small communities, scenic drives, and so on? It reads like you're really drawn to San Francisco, so maybe a small beach community would prove boring to you.
*What cost parameters do you have? You have one reference to costs in San Francisco -- yes it's an expensive place to be but as you might expect a lot depends on what you do and eat each day.
To answer one of your questions, yes there is undoubtedly a wealth of activities to keep a visiting couple engaged for 6 or 7 days. Two things to get you started to explore that idea further if you wish: one is
this San Francisco Chronicle visitor's guide where you can explore events and activities that you might be interested in. A second thing to know is that there is a public transportation system called
BART (Bay Area Rapid Transit) that will easily get you from the airport into the city and then help you get around the area, including neighboring cities for day trips. (Perhaps not renting a car would be interesting to you?)
One other note to make relative to your planning is that you could also split your time between the LA area and San Francisco -- fly into LA and see some things there, then fly to San Francisco for a few days, and home from there. LA offers public transportation too but it is more spread out and you would be more likely to want a car for your visit.
But, to answer the key question in your post: in my opinion the most stress free holiday would not be following a tour provider's itinerary which would cover a lot of California in an 11 day period, but would be one consisting of (a) flying into San Francisco and unpacking once in one hotel, (b) using a combination of public transportation and taxis to explore, (c) taking day trips outside of the city for a few of those days to see a few other communities.
Good luck in sorting through your choices and make sure to post questions as you think through this!