Girl of Many Fandoms

Okay. Trying to sort out my travel plans once and for all.

We have:

London - Chicago (flying - July 19)
Chicago - LA (flying - July 22 - Star, have you booked your flight yet? If so, what number is it?)
LA - San Diego (train, I think - July 25)
San Diego - Vegas (Road trip with Twiller and Frito! If this is for definite, that is. Guys? July 30)
Vegas - Atlanta (flying - possibly also July 30)
Atlanta - Toronto (flying - August 3)
Toronto - London (flying, possibly with layover in DC - August 7)

There we go.

Expedia, I think, is actually pushing me closer to the edge of my currently somewhat tenuous sanity. But it's the only site of its kind I know and reasonably trust.

Anyone got any recommendations for good places to book a multi-destination trip around America and Canada without it being ridiculously expensive?