I heard somewhere that

Yesterday is at best a pleasant memory.
Tommorow is uncertain.
Today is a gift.
That's why they call it the present.

So don't over-plan the trip.  But start today.  A copy of William Least Heat
Moon's classic, _Blue Highways_ is a very good primer.  If you assume an
average driving speed of 35mph for a highway trip, you'll get pretty close
this allows for kiddie stops, gas stops, giggling stops, ogling stops, photo
stops and such.

Pensionerd.

 Echoing the words of the consummate Vanagon traveler, Larry Chase, "Don't
let your dreams be dreams"