San Diego has over a half dozen rooftop bars. Due to our mild weather and beautiful skyline, there are several places to enjoy a few drinks with friends.
My personal favorite is Altitude- picture here- because you can see the most of the skyline. Coronado Bridge, Point Loma, Petco Park and the San Diego bay can all be seen from this vantage point- http://www.sandiegogaslamphotel.com/nightlife/altitude
W San Diego is a hip and unique rooftop bar with a bonfire made with stacked chairs and private cabanas. There's even a heated pool in case you'd like to go for a swim! http://www.thewsandiegohotel.com/rooftop-sandiego-bar
Summersalt is a trendy relaxing place, also with a pool and craft cocktails. Check out the Sunday morning yoga classes. The food here is farm fresh and mostly organic- http://www.hotelpalomar-sandiego.com/san-diego-restaurant/rooftop-bar.html
Stingaree has a great rooftop bar- with a dance floor and hip vibe. The dance club inside is usually way to crowded, so I always head to the rooftop for some dancing in the fresh air surrounded by the San Diego city skyline- http://www.stingsandiego.com/
Level 9 is a chill place to enjoy drinks, and also has a great view over Petco Park- http://www.hotelinsd.com/dining-in-san-diego.htm
RoofTop600 at Andaz is a chic bar with a pool, bar and lounge areas. DJ's on weekends and no cover charge.