We always rent a car when flying into Orlando. That way we can do a few things the night before/day of. Then dropping it off at enterprise and taking their shuttle is easy.
Now as for if you should drop off your crew and return the car yourself vs. all six of you dropping off the car, 50/50 on that one. Though there is an indoor waiting area for the shuttles, so for a couple in their 80s, that may be better than having them fend for themselves for a bit at the port.