I have an 8 hour layover at GIG before an international departure on UA. Though we do not have any status this year, we are flying in Global First so have some sort of lounge access. We are thinking we will take a taxi to do something during the day but would want to shower before our departure. Are there any lounges we'd have access to with a shower?

We'd consider a day rate at a nearby hotel to freshen up, but there do not seem to be many good options and the hotel in the aiirport seems to be fully booked though I somehow doubt that the websites I am checking are necessarily accurate.

Also does anyone know what time the UA check in counter opens?