Info on parking, restaurants, etc. (long)
My visit to SF included excursions to Yosemite, Marin County, and Big Sur, so I rented a car. The parking situation near the Westin was far easier than I had feared. The hotel charges about $45-$50 per day for valet parking, but not to worry -- there are two huge parking decks directly across 3rd Avenue from the hotel. 3rd Avenue is a busy one-way street with 3-4 lanes. Jaywalking is easy, but to cross to the hotel legally, you have to walk 1/2 a block to a crosswalk, then another 1/2 block back up to the entrance. Definitely worth a little extra effort to save the money, IMO.
Hearst Parking Center is recognizable as having an Office Depot and California Pizza Kitchen at its ground level. It charges $20 per 24 hours, and there was plenty of availability every day I was there. The only downside of Hearst is that it doesn't open until 6 a.m. Monday-Saturday, and not until 10:00 a.m. on Sunday. You can't get your car out of the deck when it's closed, so beware if you have an early flight out of town.
Just across the alley from Hearst is Tower Valet. Tower charges $21/day and is open 24/7. The downside is that their "day" resets every morning at 6:00 a.m. So for example, if you park there at noon on day 1, you have to have your car out by 6:00 a.m. on day 2 to limit the charge to $21. It also appeared to have PLENTY of available spaces.
I street parking is free in most areas of the city on Sunday. I parked on the street Sunday night about 2 blocks away from the Westin without any problem. Just make sure you don't park on a curb that is scheduled for a street sweeper overnight.
As for restaurant recommendations, Pazzia is a small family-owned Italian Restaurant about 2-3 blocks toward AT&T park from the Westin. The food was very good, plentiful, and less than $20 per entree. They also do take-out orders. Chaat Cafe serves Indian food, also very good and about $10-$12 per dish.
On the same block with the Westin is a Subway, Quizno's, California Pizza Kitchen, and a liquor store.
The hotel was nice too. Heavenly beds are as good as advertised.