Hi,
My husband and I use TripIt for trip planning. Although we use it primarily for sharing the big picture with friends and family, it does show driving directions between locations, and I think you can use it to help schedule stops.
You mentioned the possibility of using your phone for help...I have a Motorola Droid, and I invested in the car mount setup: http://www.motorola.com/Consumers/US-EN/Consumer-Product-.... It allows me to mount my phone on the windshield of the car to use hands-free or to make using the GPS easier to use. It also includes the charger. I've found it to be worth the cost!
That said...If phone battery weren't an issue, TripIt also has a free Droid app. And the Droid OS has "Places" which finds gas stations, restaurants, etc. near a specific location.
Enjoy the trip!