Personally, I thought that the location of the Hyatt and the Argentino, which is around the corner from it, were great. I was very happy with the Argentino, at 1/3 the price of the Hyatt. The rooms are small, but it's fine. From a quality standpoint, think of a Marriott Courtyard or Hilton Garden Inn or Hampton Inn in a prime location as comparable.

I personally am an SPG elite member, and when I went, the Sheraton was not yet built, but compared to SPG Cat-3 points rates (7K per night), I would definitely say that the Argentino at well under $100 US per night was better value, even if the Sheraton was both as nice and as well located as the Hyatt - which, in particular with regard to location, I doubt.

Proximity to most of the best dining, shopping in Mendoza is important if you will not have a car. Also, I would reitterate contacting the Vines of Mendoza prior to your trip to arrange wine touring. Their tasting room is a block away from either the Hyatt or the Argentino.

http://www.vinesofmendoza.com/

http://www.argentino-hotel.com/

Note, the Argentino's pricing on their website is in Argentine Pesos, not U.S. dollars, despite the use of dollar signs - that's Pesos. You can also book them on Travelocity or Expedia.