ah, consumer reports suggests these as the best overall, combining portability and performance
Garmin Nuvi 350 -$600
Magellan Roadmate 3050 - $600
and the TomTom Go 510 - $600
also interesting to note...
if you're on consumer reports, and it asks you for a password, if you type consumer reports password into google, the first result it gives you is from a school and it actually works... i was utterly amazed