Since LA was covered extensively above, I will give my "personal" opinion of San Francisco (just the city not the Bay Area):
1. Very small city that's easy to learn and navigate through.
2. Everything you will need is within this compact city from nightlife to great dinners in restaurants from the high end snooty establishments to really cheap eats - the choices as well as the cuisines are diverse.
3. Lots of open areas in city parks many of which are dog-friendly, Golden Gate Park being the best. Lots of free concerts in those parks throughout the year. Perfect for all types of outdoor recreation. Crazy annual festivals like Bay to Breakers that portray the carefree and open minded nature of the city.
4. Very picturesque surroundings with the bay, the Pacific, and the rolling hills as the backdrop. Iconic Golden Gate Bridge, grand Victorian homes mix with new architectural styles. Art is everywhere.
5. Cultural attractions abound from museums, opera, theater, and ballet that are available in the city if you're into that. Underground, counter culture music and art scene for those who prefer them better.
6. You're not too far from the water wherever you end up living the city.
7. Fresh produce that didn't travel too far to get to your table.
8. Sonoma, Napa, Tahoe, Yosemite, Big Sur is a 3-day weekend off trip you can plan on a whim.
1. It's cold -- it is either cold and rainy, cold and sunny, or cold and foggy. Never forget to layer when you go out. A hoodie or some sort of cover up is a must all year round. Worst time of year is summer when the fog is a daily visitor rising from the bay.
2. Crowded and narrow streets, pedestrians walk the streets in most neighborhoods, people in bicycles taking space in city roads, driving can be a nightmare as well as finding parking.
3. Sticker price shock when looking for apartment or buying real estate.
4. Co-workers with school age kids complain about lottery system in the public schools
. You're not assured of getting into the district school of your choice. Many opt to send kids to expensive private schools.
5. Homeless people and panhandlers who literally crap and relieve themselves on the streets.
1. Lots of young people in their 20's and 30's. Some people might like that.
2. Everyone is from somewhere else. Very few San Francisco born and raised folks.
3. Muni - the public transportation network of buses, train, charming cable cars, streetcars can work for you depending on where you live. Some neighborhoods have more bus lines than others but it still ends up taking you so long to get from point A to point B within such a small city. I drive to work.
4. Liberal politics and crazy extreme environmentalists.