San Miguel Allende is a small town about 275 km from Mexico City and 97 from Guanajuato in Mexico. It became an attraction for tourists due to the thermal springs and mainly because of the beauty of the colonial buildings. The temperature is nice all year around so you can also enjoy the outdoors activities such as paragliding and skydiving or just walk the city.
Also some cultural events such as the San Miguel Jazz Festival and the "Sanmiguelada", some sort of Spain's Pamplona Festival in a Mexican version... and restaurants and bars for evening/nights in the "city center".