What would be the best if we wanted to:
Fly in Friday and get a rental car.... Stay offsite the go to Seaworld Saturday. Saturday night check into Pop century and turn in the car.
Where you rent ( I would think at the airport) but I want to return the car at disney
I assume you plan to rent with
Alamo or National, based on the topic of this thread.
If you plan to return your car on a Saturday at the CCC or the Dolphin, be sure to check the operating hours in my post earlier in this thread.
If you return your car during operating hours, your return time will be the actual time of your return.
If you return your car after hours, your return time will be the time when the office reopens the next morning. Car rentals are normally priced in 24-hour periods, so this could mean paying for a second day if you rented your car at the airport Friday evening.
Also, if you return your car during at the CCC during business hours, an Alamo/National courtesy shuttle will take you back to your resort. After hours, you'll probably have to take a cab.
If you return your car during at the Dolphin during or after business hours, there is no courtesy shuttle, but you can use WDW bus and boat transportation from the Dolphin. Although there's no direct bus service to Pop Century, you can connect at MK, DHS, or DAK (during park operating hours) -- or at DTD until around 2:00 a.m. If you choose to take a cab, the distance (and thus the cab fare) is less from the Dolphin than from the CCC.