Quito is a good time. Very interesting place and probably one of the best in South America that I went to. Lots of things nearby as well. Travel within Ecuador is easy and reasonably inexpensive if a bit slow. Air travel is pricy. Prices are reasonable and you will probably want to stay in Mariscal if youre on a budget and want to be in the thick of things. Most guidebooks will say it's dangerous but just have a bit of common sense and youll probably be fine. I never had a problem and was there quite a long time. Santiago is a bit dull but it has its moments. More expensive than most of the rest of SA I have been to. Food is good, easy to get around, reasonably clean and safe. There are few great reasons to go to Lima instead of other parts of Peru. Go to Cusco or Arequipa if you go to Peru. Lima can be pricy, but in any case be careful. Outside of Lima is very cheap and very interesting. Haven't been to Rio.

Personally, if I were going to South America, I would go to Easter Island. Not because it's the best place on the planet, but because it's very, very expensive to get to and this ticket provides a reasonable cost of getting there. Lodging is pricy but not out of the world and the island is fascinating. It's actually a bit creepy in a way because there are few trees, it's a temperate/desert climate, there are very few people, and you really feel like you are in the middle of nowhere...which you are.

If you don't speak spanish, try to learn a few words before you go. At least try to pronounce things. It's not crucial but it will make your life a bit easier and will help guard against getting ripped off.