My dh and I took an adult only trip to SF two October's ago. It was WONDERFUL. We didn't stay for a whole week, but we were able to do some really fun things. My cousin lives there, so she took us to a few places, but mostly, we did our own thing. One of the things we did was an eco-van tour of Muir Woods and Wine Tasting. We went to Sonoma and visited three vineyards, with a stop in the town on Sonoma for lunch on our own. We had a GREAT time....We did two smaller vineyards and one larger one...the smaller ones were AWESOME, because they gave us full-sized glasses and not just sips, of wine! It was really really fun!
We also did a night-time Alcatraz tour which I highly recommend, and we did the other touristy things like riding a cable car, and Fisherman's Wharf.
We live about an hour and a half from NYC and while it is fun for the day, I really don't think I could spend a week just in the city. There is only so much money for Broadway Shows, and you can only do so many museums. After that, what's left? The other touristy stuff doesn't take that much time to do...