I know that check-in at GRU can take some time. As a 1K what should be a reasonable time to go to the airport and check-in, flight departing around 2100? Would like about an hour prior to flight time to spend in RCC.
" - - to go to the airport and check in - - "
What time you go to the airport depends on which day of the week you travel and where you will start out to travel to the airport. If you travel to the airport on a Friday night it takes nearly twice as long as any other day of the week.
For your 9:10 flight you should know that check in opens anywhere from 2 and one-half hours - three hours before flight time. Therefore, check in will open between 6:10 and 6:40.
There is a separate line for 1K and Business and * gold. The line generally moves fast once the check in begins.
After check in, you proceed to airport security/screening and immigration. don't forget to have the agent affix your departure tax sticker otherwise you will have to return to United to get it.
Immigration timing is unpredictable and can take as long as 45 minutes (on a Friday night) or as short as five minutes. This depends on which day of the week you travel.
The RCC is right around the corner and up the escalator or elevator, whichever you chose.
I hope this helps with your schedule planning.