Hyatt hotels in Mexico vary considerably in location, size of rooms, etc. The Hyatt I find the most pleasant is in Merida, Yucatan. It is outside the congested Zocolo area, it is within a short walk of the archaeology museum (Palacio Canton, Museo de Antropologia).
Several other good hotels are nearby so you can expect all kinds of restaurants in the area, and naturally the hotel itself has plenty of restaurants. Yucatan in general and Merida in particular are relatively safe so you can get some exercise walking up and down the Paseo Montejo in the cool or the evening or early morning.
Address of the Hotel Hyatt Regency Merida is Ave Colon esquina Calle 60 (100 meters from Paseo Montejo).
tel 52 999 942 1234, fax 52 999 925 7002. email: email@example.com