Seaport Village is cool though very touristy-lots of cool little shops/boutiques. Expect pricey. They have the best little shop that sells ceramic tiles for all sorts of uses-I still have mine framed in my kitchen. Lots of neat kids shops too like kites, toys, personalized things like banks, shelves, footstools, etc.
Hotel del Coronado is cool-we walked around the hotel and the pictures are so fun to look at.
Old Town is fun and can't be missed. Great food, historical displays, lots of Mexican shops (and non mex), live music, and of course you have to eat there! It can be really busy but we went in the summer both times so April is probably slower?
La Jolla is upscale and fun to visit. great beaches and more boutiques. Fine dining too