All of the codes that have gotten me good prices at the airport gave me the same base price at the Car Care Center, but I didn't have to pay quite as much in taxes at the CCC as I did at the airport. You also have the option of renting at one place and dropping off at the other.
We picked up at the CCC because we had a decent amount of luggage that I didn't want to have to deal with. So we took ME to Disney and the shuttle to the CCC a few days later, when we were ready to pick up our car. Since we did a split stay and moved offsite, we dropped off at MCO.
Definitely reserve ahead of time. Just showing up and renting at whatever the "rack rate" is will end up costing you 2-3 times more than reserving ahead of time with a good code and a coupon. Unless you go with a "pay now" rate or something like Hotwire or Priceline, you'll pay at pickup.