I've always found going to each states tourism website (just google state name and tourism) very useful. If you're planning far enough in advance, they can send you brochures, road maps, and extras relating to any particular interests - sports-hiking etc
scarlett Travel Republic is good for flights; only in that they accept a deposit beforehand and you pay the rest later, eg my flight this summer was 700; I paid 225 in December to secure it and the rest later .