Looking for an area with good nightlife and things to do within walking distance.
1. Yay Linda! 2. Nerrticus
The best spot for nightlife and action within walking distance is downtown near the Gaslamp District. Hands down. Clubs and bars and live music everywhere.
There are a few hotels up near A and Ash Street that are cheaper and much quieter than right in the middle of the Gaslamp, and are a only a 6-8 block walk (or $5 taxi ride) from the Gaslamp. From experience I can tell you it's a safe walk at any hour.
Pacific Beach is an option, and if money is no object you could head to La Jolla or Coronado Island, but I think downtown is what you're looking for...Good Luck!
Scripps Ranch, Del Mar, Pacific Beach, Ocean Beach, Carlsbad, Downtown.
4. Joe C
Pacific Beach or Downtown
Both have lots of nightlife, resturants, and bars
One of the best deals for an oceanfront hotel is the Blue Sea Lodge in Pacific Beach (PB). http://www.bestwestern-bluesea.com/
Downtown is expensive but it's right on the trolly line which extends your "walking distance"