I live north of SF. I'm late to this thread, but wanted to give this area a push.
I've lived in the Chicago area and Boston area. Both are beautiful and I adore New England. I hope to return there some day (when the economy actually has jobs).
For now, though, I live in the Bay area and have for 5.5 years. I had family recently visit in June. We spent a week doing events. I told them that they could come back again and I could take them on a whole new set of adventures and not repeat one thing (or if we did revisit an area, it would have different sites to see).
The extended Bay area has all sorts of fun things to do - all depends on your budget and time. These range from wine tasting (some places are even free!), hot air balooning, plays/musicals, Fisherman's Wharf, boat rides, Angel Island, Alcatraz, visiting the giant Redwood trees (you can drive through some!), Winchester Mansion, Mystery Spot, Charles Schulz Museum, Lagunitas Brewery (some of the best beers I've ever had - and they give free tours with free beer!), dozens of restaurants along the ocean/bay or various rivers, beaches, amusement parks, etc., etc.
Plus, from June through September, it pretty much never rains (some exceptions) allowing for a lot of outdoor events. Many BBQ's, sun, tanning, swimming, etc.
If I were wealthy, I'd "summer" every year here, then go to New England for the fall and early winter.
Anyway, I hope you enjoyed your visit and will come again.