We have been to USA in 2012 and 2013. Both times booked all our own accommodation online direct with hotels/motels. I found prices were better than from Wotif etc. Good discounts if you book a early.
2012, flew to New York and drove back to LA via "all of the US"..LOL
2013, flew to LA and then to NY.
Booked the air fares via a travel agent and got good deals through Virgin Aust.
There was a travel expo in Sydney recently, so not sure when the next one will be.
Next trip, in May 2015, is via Hawaiian Airlines to Las Vegas and back to Hawaii. They seem to be advertising good prices at the moment..