As a singer from the US, I haven't been part of loads of UK festivals, but in one trip, I was booked at the Dartmoor Festival in Devon, Whitby in Yorkshire, and Wadebridge in Cornwall. Each was good for different reasons: Whitby is BIG! Dartmoor is small and comfy. Wadebridge is middlesized and beautifully organized.

Good idea if Americans want to travel to England during festival season is to check out the newsletter lamarca mentions a few posts back. It'll give you an idea of what's going on, where, and who'll be performing, so you can plan to go at the best time. j