To be honest we stayed in Tuxtla an extra day because our hotel room is quite comfortable.  Guidebooks seem to skip over Tuxtla and really the city has little to recommend staying more than a day or two.  It is sprawling low rise buildings.  The buildings in the center are old but not in a historical sense. We can see the Sumidero Canyon in the distance from our room.  It's too hot here this week but it's not always this hot.  The temp is still about a 100 outside.  In spite of that we walked to the anthropology and history museum.  The museum had some nice artifacts and we tried to learn a little more about the other cultures that were here before the Spanish arrived.  Sadly the museum is not air conditioned and we asked the security guard about that.  He said the system was thirty years old and broke down six years ago.  It had not been replaced because the government could not afford to do so.  The stone and ceramic artifacts probably don't mind the heat but it can't be good for the paintings and the textiles.