National has a spot at the Swan/Dolphin.
We used Dollar, and got a great rate. Little known info, and which the agencies are hesitant to tell you - they will come pick you up.
We had ressies at Dollar - airport to pick up our van the fourth day of our trip. We called BCV's and got the number of the company. Instead they gave us the one in Lake Buena Vista. Initially they couldn't find our ressie, since it was made with a different location, but once they had our ressie number, they were more than willing to come get us, bring us to our van, and let us return it to the airport with no extra fees. I highly recommend them, plus with the codes you can get great deals.
In regards to the pickup - obviously they don't want to pickup your whole party and luggage. Send one person to go get the car and come back to the hotel.