This is a list of Mexican symphonic rock bands of which I am aware. I cannot recommend them all, as I have not heard them all, but most are pretty good. Sorry, I cannot be more specific:
Caja De Pandora
Cast
Codice
Cronico
Flüght
Galie
Govea
Jacques Menache
Marco
Saena
Toccata
I did some digging on these bands and I ended up D/L Alba y ocaso by Codice and ripping it to three CD-Rs. Some gorgeous acoustic strings and wonderful winds and drenched in some excellent keyboard work. The vocals are very limited which is probably a good thing as I have hard time with foriegn language vocals. Two hours and it kept me engaged right through the end. Sure lifted my spirits yesterday on a windy, rainy, chill to the bone day.