Hi, Peter. Have a wonderful time in CUN. BTW--for hotels: We usually stay at the North ATL area around Virginia Avenue--close to lots of food options. Th Wellsley Inn has good rate for nonrevs. 404-762-5111. I don't understand CI question. I think you mean the terminal? You check into main DL terminal, check any bags and go thru security. I would allow 2 hours minimum for check-in. Once through, you take the "plane train" to each concourse. DL doesn't upgrade other airline employees, but it can be rare for employees to move forward on a very popular route!