A few of my favorite viewing spots in SF:

1. Pier 7 : As you walk down the pier you'll get great views of the bay and the Bay Bridge And as you walk back you'll get a great view of the SF skyline, the Ferry building, and Coit Tower. 
2. Cupid's Span
   
3. Bernal Heights Park
4. The Southwestern corner of Dolores Park 
5. Top of the Mark
6. The View
7. Angel Island
8. Sunset at Sutro Baths
9. Battery Spencer
10. Lake Merritt
    

There are a few places that I love, some of which have already been mentioned. Coit Tower is cool, but just a bit touristy, and not my favorite view, since there are a lot more natural views around the city. For views of Golden Gate Bridge, I like Lands End, which is a great little trail around the sea cliffs. For the other side of Golden Gate Bridge I love Battery Spencer, which has great views of the city as well.

The hills and steps around 16th Avenue Tiled Steps Project are good, as is a couple different around around the Haight District, like Buena Vista Park and Corona Heights Park. My favorite, however, is without a shadow of a doubt, Twin Peaks, what I believe is the highest point in the city. I'd recommend going up there at sunset and getting some great sunset/twilight shots. Love hiking around up there, but bundle up, since it can get really windy up there. 

Search for 16th Avenue Tiled Steps Project , you will get an awesome view of water and the city. Hike up to the top. 

Check out Twin Peaks on a clear day. Some of the best 360 views in the city. Several other parks in the area also have great views. Corona Heights Park, Tank Hill Park and Kite Hill Open Space are a few to checkout.

Coit Tower is a must to see.

So many!! One idea not many folks think about is getting out on the water. Lots of ferry options can get you good views of the city that way. We like to go over to Angel Island for hiking, and it has some sweet views of downtown from across the water. The Presidio has a ton of trails that put you in great view of the Golden Gate Bridge: Lands End (Mile Rock Beach), China Beach. The tee box on hole 17 at Lincoln Park is fantastic (just don't get in the way of the golfers). Also check out the Mission District and Bernal Heights -- unique neighborhoods with funky art, shops, and people. Mornings are lovely on that side of the city because they get great light. Enjoy!

I would also go to Hawk Hill for an incredible view of the golden gate bridge with the city in the background.

It seems I Googled this very question not too long ago (I put in "photographing san francisco"... the first two links are quite good) One place I like to photograph, and I believe its the intersection of Taylor St & Bay St (in that area) when a Cable Car comes up the hill, its easy to get a shot of the CC & the bay behind it (there is little traffic & you can step out into the street... carefully, of course... to get your shot).  If you find the Painted Ladies (at Alamo Square) be sure to walk up the hill a bit to get the classic shot with the city behind them.  Also, don't be afraid to get close-ups of signs, etc.  (I hope I've posted one of my favorite photos of Fisherman's Wharf)

Jack Early Park .. a hidden telegraph hill gem .. virtually unvisited. 

I'm a huge fan of Twin Peaks. You can seriously see every corner of the city. It's gorgeous up there. 

If you're looking for a place to take a cool shot of the Golden Gate Bridge, Crissy Field is another good spot. 

I was recently in SF and loved the views from Fort Point National Historic Site. You really can't beat the Golden Gate Bridge pics you can snap here.

Also, Top of the Mark is one of my favorite cocktail bars atop the Mark Hopkins hotel for great night views and cocktails. They usually have live music as well!

The top of the Lyon St stairs at Lyon Street and Broadway.  Another good one is at top of the stairs at the intersection of Broadway St and Fillmore St.  And yet another that will take your breath away is at Fort Point National Historic Site from which you are essentially under the Golden Gate Bridge.

Hey Kenneth,

For parks with views, SF is your place. Several parks will have beautiful vantage points. The big spot is (highest point in SF) but I personally love Corona Heights Park (second highest point in SF). Corona Heights is definitely less known by from tourists. You can post up and sit on boulders that give you a 360 view of the city. A lesser known park that mostly locals go to is Grand View Park located in the Inner Sunset. On a clear day, it has a great view of the city and really cool steps leading up to the viewpoint.

For a fun and beautiful hike with a view I'd also check out Lands End. Great fun and easy trail with awesome views of the bay and Golden Gate Bridge. The renowned Dolores Park. If you aren't familiar with it, it's a park that has little rules and great for people watching. Also, it has a pretty cool view of downtown SF. The park gets packed on hot days with fun and eclectic people with several different types of pets (I've seen macaws here).

You've got plenty to choose from and this is just scratching the tip of the iceberg in regards to viewpoints in SF. Have fun!

The Marin Headlands has a beautiful, unobstructed view of the city. The hills of Sausalito offer beautiful views of the city with the bay. Also the top of the large hotels downtown have bars/restaurants that offer outstanding views. Have a terrific time!!

3 of my favorites:

1) Top of the hill in Bernal Heights

2) Cafe at the San Francisco Art Institute

3) Observation Deck at the De Young Museum

Best views of the bridge are from the "other" side-head to Golden Gate National Recreation Area-it's a large area, but if you head west out Geary Blvd, when it hits the water-park you car and walk north along the hiking paths!

If you would like spectacular views of the bay and a unique experience, hop on a ferry! I made a video about the SF Bay Ferry that you may find interesting: https://youtu.be/8RvV2-N7K30