In reply to davidrj1:
You need to have a look at this
http://www.andes.org.uk/andes-guidebooks.asp or some of the info on that site.
If you're inexperienced and looking for something up to PD, but over 6000m, the best of the Blanca peaks might be a bit much.
Bolivia has easier 6000ers, with slightly better access and weather. Parinacota is extremely easy, technically even easier than Huayna Potosi, which is regarded as one of the easiest and most popular Andean 6000ers. Sajama is quite high, and only a bit harder than Parinacota, and they're in a beautiful area. Illimani is mostly straightforward, with good access, but can have variable climbing up high re: crevasses, and the route up to high camp is awful.
Ecuador is also popular, and has two seasons, but I've never been there. Conditions seems changeable in recent years, plus they now forbid unguided climbing above 5000m (maybe not relevant to you, but not something I would support).
There are dozens of suitable high peaks in the central Andes of Argentina and Chile. Some of them might be a bit boring, others are much more interesting but hardly visited, so hard to arrange access. It's also a Nov-Feb area, whereas Peru/Bolivia is May-August, so it depends when you can go.