A week and a half ago I first used Expedia[a] in anger. I had planned on driving across the USA, but as one person told me "that will be pretty damn boring most of the time", I decided to see what the price would be to fly across the USA, stopping at the fun places only.
So I went to Expedia. Some lessons learned:
Register, get an account. Being able to have an itinerary is required for advanced use of the site. You'll be able to tweak your trip much more.
You can book trips of any complexity by first setting up your flight route, and then attaching rental cars and / or hotels to the points where you stop.
As soon as you have finalized your dates and your flights, book them. I could have flown for $680, but ended up paying $1100 because I was slow to book. Learning by pain...
But it looks like it'll rain every day I'm in Maui, so I guess you get what you pay for...