There really isn't much for Mexico. I remember back in the day there was a very good freeware scenery for the whole yucatan peninsula, merida, cancun etc, but this was for FS98. For FS2004 there are some kind of dissapointing sceneries out there for MEX
. Although there is an AFCAD for MEX
that is very good and accurate. But it's been a while since there has been anything better than what there was for FS98.
If you want payware, these guys are very accurate and do they're homework.
*I've never owned any of their products, but from the screenshots I can tell they are extremely accurate to the real airports.