Total consensus:
DONT MISS RIO DE JANEIRO, the wonderful city!
I'm flying on a DL award and they don't have any obvious South American partners unless I could fly TAM using a codeshare on KLM or Air France
DL has daily nonstop flights GIG-ATL, so no problem, you can fly to EZE and return from GIG.
From
EZE to GIG you better book your ticket in advance because flighst are usually fully booked. You have the following options:
AR: operates twice daily nonstop
RG: operates twice daily nonstop
GOL: operates daily with stop-over in GRU (probably the cheapest option. You can buy your ticket online if you live abroad with AA cards:
www.voegol.com.br GOL is a LCC.
TAM: one weekly nonstop on Saturdays (dep. EZE 3am arrives GIG 6am), flight will be increased to daily in June/06. Two daily via GRU.
Alternative, you may fly EZE-GRU with LH B747 or BA B747 and buy a separate ticket GRU-GIG with TAM, RG or GOL.
Hope the info was useful.
Rgs,