We also stopped in San Miguel de Allende on Sunday in the early afternoon. The traffic was awful since it was a holiday weekend and we almost gave up on finding a decent place to park where we could also leave town after, but we lucked out and missed the worst of the traffic on one road and tried entering a different way and had much better luck.
Ignacio Allende was another of the leaders at the beginning of the War of Independence. He was born in San Miguel (el Grande at the time) and the name of the town was changed later to honor him.
The center is a World Heritage site and the town is a very popular tourist place for Mexicans, especially with its history and not being too far from DF. It's also one of the hot spots for American and Canadian retirees. At least it didn't feel as overwhelmingly American as some places in Chapala do.
I liked Guanajuato better though. SMA was a little too close to being cute in a lot of places. GTO is fascinating and charming but almost never cute.