OriginalWheelman wrote:I
Things we're into:
Cars, History, Museums, Nature, Boating, Tech stuff
Things we're not into:
Clubs, Crowded places, overly "Artsy" stuff
Things I have considered:
Griffith Observatory - Love space
Napa Valley Wine Train - train ride through the valley with lunch / dinner and a wine tasting / winery tour
Renting a convertible - er, duh
going to Long Beach -
Sightseeing in San Fran
I know NICO will have better ideas.

A few ideas that follow your criteria
San Fran area:
cars: you're not that far from Laguna Sega, driving the 17 mile drive, check when the Monterrey historics are.
wine country" plenty of choices. Train ride is one option, you can also visit a specific winery of something you drink regularly.
nature: Muir woods is nearby (redwoods and sequoias)
sightseeing in SF (mandatory)
history: too much to list, but alcatraz, lombard street, riding a cable car, fisherman's wharf are must do's.
Long Beach is a nice staging point for southern CA. Personally I could spend a week in San diego.
history: the Queen Mary in Long Beach is a nice place for cocktails.
cars/museum: Peterson Automotive Museum (impressive)
boating: Catalina Island.
nature: Aquatrium of the Pacific (in long beach) San Diego Zoo (one of the better ones in the country), many nice beaches
stay away from : Tijuana, unless you want to see squalor.
romantic: sunset champagne balloon ride in DelMar. An added bonus, if the winds are right you could whizz on Janet jackson's estate from high altitude.