Remember your West coast friends could do SFO/LAX/BJX, that would save having to get to SFO for the early flight to ATL. Or, depending on loads everyone can meet in LAX or ATL. I have not been to that area but have been interested in
SMA. Outside of BJX is
Guanajuato, I hear the chain hotels have free shuttles. You could spend a day or two in
Guanajuato then
taxi/bus/shuttle to SMA. The town of Leon is also in the area of BJX, have not looked into anything about Leon.
Cuernavaca is some distance from the state of Guanajuato, unless you fly into or out of MEX.