Either,
1. Tuscany. Went there with my school (music tour). Got to see Florence, Pisa, Lucca and the west coast.
The views and weather were great and the region overall is a cultural hive.
2. California. It was quite a few years back but there are quite a few good things I remember, chiefly Disneyland and universal studios (I was six at the time but I'm sure they're good fun all the same) and the Redwoods forest. We also went to San Francisco and up Mount St Helens, among other places, so there was a good variety of things to do.