Fun Santa Monica hotels under $400/night?

I think Fairmont Miramar Hotel & Bungalows is the best choice with the adjacent Bungalow as a fun nightlife option.  Shore Hotel is a privately owned hotel but don't let that scare you off.  Oftentimes the rates are lower than they should be and the location on Ocean Ave is excellent.  Great Mexican restaurant there too called Blue Plate Taco  

Shutters On the Beach is on the beach and walking distance to both Santa Monica downtown and the Main Street area. They have a nice bar and restaurant there too. 

First choice, I'd go with the Fairmont Miramar Hotel & Bungalows. Vibe is good and their lounge Bungalow always has some action. Second choice would be The Huntley Hotel. Restaurant/club there is worth a visit too. Called The Penthouse. The newer Shore Hotel looks nice too although I haven't been.  

If you want to try a little further south in Venice, the Hotel Erwin is probably the hippest place in the area right now.