An American Adventure in 2013?

I've been thinking. Next year I'll be 30 (eep!), so it might be a good idea to do the US trip I've been talking about. If possible I'd like to do a multi city trip (maybe a week on the East Coast and a week on the west) as that isn't much more in terms of flights (It was about £200 more for a London->Boston->Los Angeles multi trip then for a London to Boston return).

Suggestions for destinations, cheap but decent hotels (ie a bit like the UK Premier Inns) and things to do/see would be much appreciated!