When you say "regional" Mexican you are talking about tuba's and accordians. Most folks think of "Tex-Mex" music......
Tex-Mex, or Tejano music, is not Mexican. It is from a very small area of Texas, and only one a handful of stations today... maybe 4 or so.
If you have ever seen a "regional" mexican band you will have to agree it is some of the most amazing music on earth. The drums, with one snare, a high hat cymbol, and numerous cowbells are just too awesome for words!
Regional Mexican is actually many different types of music which, originally, came from different areas of Mexico. The tuba stuff is "banda" and from the northern Pacific state of Sinaloa. The accordeon stuff is "norteña" and comes from NE Mexico. "Grupera" is the keyboard fusión of classical Mexican sounds with ballada and pop and cumbia. Ranchera is what a Mariachi plays. "Cumbia" is an adaptation of a Colombian rhythm that is now typically Mexican.
There are examples of these styles are on www.hispanicformats.com
I learned to love the tuba at a Martin Mull show one nightat the Great S.E. Music Hall while using corrective medications with a stripper lady known affectionately as "River Deep."
Bring on the Tex-Mex in wide glide FM stereo......
Tex-Mex is on life support, and only appeals to really old demos in places like San Antonio. It's funny, because the jocks are usually totally English speaking. Tex-Mex does not use tubas.