Hi Valerie,

Top 3 is TOUGH! But here goes:

Three things to see:

1. [free] + Ocean Beach (this is really a single stop)
2. [free] Bridge to bridge view from the top of Twin Peaks
   
3. [free] Palace of Fine Arts + Crissy Field
   

Three things to eat:

1. [$5-15 pp] If you venture to the beach area, Outerlands $5 best cheese is the best thing to have for lunch! The line can be crazy long though, so don't go hungry :)
   
2. [$5-10] The olive oil ice cream at Bi-Rite Creamery is to die for! The brownie sundae is also fantastic.
   
3. [$10 or less] Papalote has the best burrito in SF. :)
   
   

Three things to do:

1. [$18] See a show at the The Castro Theatre
2. [free] Walk the Lands End trail
3. [free - unless you buy something!] Explore the shops on Valencia St in the mission, Hayes Valley or Union St + Chestnut St.

I've put together a few more of my faves here if you need extra ideas. Have the best time! :)

Go to the Ferry Building and eat a sandwich at Boccalone Salumeria, and an ice cream at Humphry Slocombe.  You can also get a grilled cheese sandwich at Cowgirl Creamery.  The Ferry building is certainly touristy, but those are world class culinary options that are inexpensive and happen to be in a tourist attraction.  Also, if you're there on a Saturday, the Ferry building has a good farmer's market in front of an behind it.  Another inexpensive local option, that isn't touristy but it's in a touristy area Union Square, is Super Duper Burger.  Good high quality burgers and fries, that won't break the bank.  Just don't compare their pricing with fast food, it's expensive compared to junk from a chain but worth it, instead compare it to other restaurants and you'll be thrilled.  

For beer Lovers Toronado and Zeitgeist

Half touristy/half local, give the views and history a try at Cliff House-and the popovers are amazing too.  Love the SoMa StrEat Food Park-the trucks change daily.  And for an hour long wait with your newest best friends, try Tartine bakery-the best croissants, coffee, quiche and desserts.  Great for weekend brunch.  We are also big fans of the fun experience at Tonga Room & Hurricane Bar-make sure to stay long enough to see the thunder storm.

For excellent food in China Town, try peking duck at R & G Lounge or anything at Oriental Pearl Restaurant.

Scott also requested that Beach Blanket Babylon be mentioned.  We had a great time there on New Year's Eve.  So funny!

Ditto on the Sutro Baths.

FREE to see/do:

• Coit Tower or Twin Peaks for the views.
  
• Walk or drive down Lombard Street
  
• Drive through Golden Gate Park and stop and visit Queen Wilhelmina Tulip Garden.
  
• Walk through Clarion Alley and check out the street art.
  

Food:

• Stop for chocolate or ice cream at Ghiradelli Square.
  
• Try dim sum in San Francisco Chinatown (not the best, but definitely the most touristy/iconic area for dim sum).
  
• Have a slice of pizza at Gaspare's Pizza.
  

Go to "Off the Grid" on Sunday afternoon in the Presidio (if the weather is nice) - http://offthegridsf.com/markets/picnic#food. From there, you could do some hiking - whether its on Crissy Field, Baker Beach (beware of old man nudity), Presidio trails or across the Golden Gate Bridge into Marin County.

Hang out in Golden Gate Park or Dolores Park. Hike along Lands End. 

Alcatraz, Haight-Ashbury, Ferry Building