When you go on vacation and what you want to do on it are big determiners.
If you want to ride, anything in the northern half of the US
needs to be done in summer.
If you want wide open and rugged, the West is the way to go.
The east is more riding through forests.
If you want to see the leaves turn (very pretty sight), it can be a tricky scheduling for the right time.
Check out the Discovery channel and Travel channel websites
to give yourself an idea of what you want.