I was very impressed with this tour across the US and into Mexico on a single speed:
http://www.crazyguyonabike.com/journ...doc_id=339&v=0
The bike is a Surly 1x1, so it's not exactly a cheap supermarket bike though. I've never ridden a cruiser, but the riding position looks terribly uncomfortable to me (and the bikes themselves look ugly as sin...). I'd rather try a good used bike for touring.