Eileen has already mentioned that she's going to San Diego (there's a song in there somewhere). I've only been to San Diego once - the year I joined Microsoft - and it was jolly nice city for a conference, although after the flight back I asked our travel agents to make a note that I would rather fly Aeroflot connecting in Moscow, than fly with United again.
I fancy going back to San Diego, if for no other reason than I want to dive the Yukon - I've previously dived her sister ship the Saskatchewan and will probably be going back to her in the summer, but she's in the chilly waters of British Columbia. Californian waters are somewhat warmer - Eileen's a diver too, although she might think even Californian waters are a shade cool.
A better reason to go to San Diego in April is the the Interact conference. This looks like a great event, and there is a limited offer at the moment from Gurdeep - a free ticket to the US tech-ed or IT forum (he says 09 on his post, but I think it is this calendar year - but our Financial year 09). If you were thinking of going to the European the saving on a free ticket would more than cancel out the airfare. So get your skates on and check out his post.