In reply to jon h:
At frey there is little below E1, fyi. Incredible venue, definitely near the top of the list especially if you are walking as it is a popular area for that too.
Valle Encantado near Bariloche is apparently excellent.
Piedra Parada on the way from south argentinian pata to bariloche (if that's the direction you're going?) is fantastic
Bolivia has loads but I haven't been
Hatun Machay is unique and Huaraz itself is a base for fantastic walking
Loads in Chile too
Are you taking climbing gear? When are you going? How long for?