San Miguel de Allende

There are so many delightful "on the beaten path" things to do in SMA, I have a hard time pointing you toward anything less well-known.

Have you checked out Atlas Obscura? https://www.atlasobscura.com/things-to-do/san-miguel-de-allende-mexico

If you will have a car and are up for a drive out of the city, I'd recommend Mineral de Pozos, about an hour drive. The abandoned mines and haciendas there are fascinating.

Also, Dolores Hidalgo, about a 45 minute drive from SMA, is Cuna de la Independencia Nacional (Cradle of National Independence). If you're interested in Mexican history, it's worth visiting. A few decent small museums tell the story, though most of the exhibits are in Spanish only.

Lunch at one of the stands in el mercado. Tacos from Andy’s Tacos. I haven’t been, but the city of Guanajuato may be an option.

Just north of the town on the road to Dolores is La Gruta - a pleasant and low key spa complex that's worth a visit.
The nearby village of Atononilco might be of interest too. As I recall it was from the little church there that the insurrectionists of 1821 collected the banner of the Virgin of Guadalupe that became the symbol of the revolution.
You can get to either by local bus from SMA. Can inquire at the Biblioteca for specifics.

Don't know the TA list, but Santiago de Queretaro, or just Queretaro. There is a nice colonial center and a very interesting aqueduct. It's about an hour or so by bus. Previous posters named Dolores de Hidalgo and La Gruta and they are good places to visit also. "On Mexican Time" by Tony Cohan is a good book to read in advance of travel. Its been a decade and a half since we were there so I worry that all the gringos have wrecked San Miguel by now.

The biblioteca publishes a weekly bi-lingual newspaper called "Atencion San Miguel" that's pretty handy for seeing what's going on around the town . They also have a number of special interest tours that might be of interest, including one to Pozos which a previous poster mentioned.
I second the suggestion of Queretaro - a very pretty colonial town. I think the last of the silver mines is ,located there - the last vestige of Spanish rule.
Might add that we booked our tour to the Monarch Butterfly Sanctuary from SMA. We considered it to be one of those once in a lifetime experiences.

Thank you all for the excellent suggestions. Walked the Barrio de Guadalupe yesterday, heading to El Charco today. The spa town sounds great too. Thanks so very much. Peggy