Itinerary ideas?

I was thinking we could fly into DF, spend a few days there then fly ($480 roundtrip less than 2 hours) or bus (about 100 bucks - 17 hour trip - Mexican buses are really nice though) to Campeche (or check this out) in the Yucatan, rent a car and cruise around the little indigenous towns along the Guatemalan/Belizian boarder checking out all the crazy Mayan ruins along the way. The fly/bus back to DF for return flights.

so that would look like:

1. Fly to DF

2.DF

3.DF

4.DF

5. Fly or bus to Yucatan

6.Campeche/Roadtrip

7.Roadtrip

8.Roadtrip

9.Campeche to DF

10. Fly to USA

Other ideas?