Check out a site I recently came across, www.maps-of-mexico.com
It is a fairly detailed map site which breaks down each Mexican state into grids. Living in the southwest corner of Arizona near where the Mexican states of Sonora and Baja Norte meet, a good crossing from the US into Mexico is at Algondones. It is the last town in the state of Baja Norte to the northeast, and is easily accessible from U.S. Interstate 8 in the far southeast part of California right before Arizona.
Once you get into Mexico (assuming you are coming through the US), a good town is on the Sea of Cortez called San Felipe. There is camping north of there. A pilgrimage can be made to Mike's Sky Ranch which is one of the stops on the annual Baja 1000 race. It has cult status among bikers because of the Baja 1000, although I have not been there (yet). On the Pacific Coast, there is the wine country, and the port city of Ensenada. Get some other places from other HU members, and then check the maps for Baja on maps of Mexico.com Have a good trip!