Mendoza is a province in the Cuyo region of Argentina, located at the center-west of the country 1,098 kilometers from Buenos Aires and backed up against some of the most impressive peaks of the Andes. It is sunny, dry, and warm for a large part of the year which makes it ideally suited for the production of wine, and it is this reason - along with great horse riding, rafting, and trekking on Aconcagua (at 6962 m, the highest mountain outside the Himalayas) - that most people come. Indeed you haven't gone to Mendoza if you haven't tasted its delicious wines. Mendoza's most famous grape is Malbec from Maipú and Luján de Cuyo, but very good Cabernet Sauvignons, Pinot Noirs, Merlots, and Syrah are also grown in the area.
Some hotels will let you use their facilities (gym, spa, pool, beach, etc.) for a reduced day pass. This can be great for layovers!