If you need some ideas in Spain, Mario Batali has a like 16 part mini-travel series through Spain with Gwyneth Paltrow. The series is probably like 70% them eating food, but otherwise it is very thorough in its adventures through EVERY BIT OF SPAIN, including some islands.

I would do Spain/Portugal, or maybe see how bad it really is in Istanbul in mid-March (and other cities you want to visit there), otherwise like other people say - Iceland is pretty neat.

Those JetBlue vouchers probably sound mighty appealing, and there's probably no where in America that is going to be THAT exciting. So uh, there is that problem. JetBlue will certainly take you to the Caribbean as you know.

If you haven't done the Pacific Coast Highway, why not just do that in March? Or make it a week long trip and rent a car in LA, and drop it off in Seattle (and fly back to LA)?