G.B.
I don't know where you live, but one of the cheapest vacations we took was to Washington DC. Almost everything is FREE! We had a car since we drove there, but used the subway system to almost everywhere we went. We stayed at a Day's Inn in Arlington, VA that was less expensive and a block from the subway. When we travel now, I generally don't book a hotel unless they have a continental breakfast - one meal saves a tremendous amount. My favorites are Hampton Inns, now, but I use Tripadvisor.com to help find a decent hotel.
Hope this helps - good luck!