You can take a plane from Mexico City (around $300USD), it's just a 45 minute flight with some scenery, nothing otherwordly. Beware, the taxi from the airport to central León will be around $30 USD, and a 40 minute drive.
Mostly, visit the historical center and shop for shoes. There are lots of cheap places to buy shoes and leather in general, some outlets on the sides of the manufacturers. There is also retail outlets of leather goods that are relatively cheap when compared to Mexico City or Guadalajara. Remember this is not even a capital city, so there is not much to do.
Hotel Mexico Plaza*: Free Wi-Fi, though somewhat distant from the main city (around 20-25 minutes on a cab). Taxis from the airport are by no way cheap, around 20 USD, and transportation to downtown is around $5USD. Rooms start at $50USD the night.