Spend your weekend in the Mayan Rivieria. Dedicate 2 days to colonial Merida and the Chichen Itza ruins and end with 2-3 days at a beachfront resort.
One Week
Combine 3 days in Mexico City with 3 nights in San Miguel de Allende or Puerto Vallarta, making time for a day trip to the Teotihuacan ruins.
Two Weeks
Pack in a 4-day visit to Mexico City, 2 days in Cuernavaca, and 5 nights at a resort on the Mayan Riviera. End with two days in colonial Mérida to visit the Mayan ruins.