I'd do GRU because I have friends there, but why GRU over GIG otherwise?
Spent a year in Brazil, most shabbosim in GRU and a single shabbos in GIG. GRU has excellent Chabad’s on Shabbos day (some also on Friday night) that serve full meals.
GRU has greater variety of good food.
GIG is nice, though can’t compare the Chabad Leblon to the ones in GRU.
GRU also has some great markets and historic places open on Friday/Sunday. Wins over GIG IMO.
IGU can be doable within t'chum if you stay in the AR or BR park, no?
No taking pictures? Also cannot do activities.