We were just there last week and booked a "7 pssgr mini-van". It said Uplander or similar. In the Emerald Aisle minivan area there were Grand Caravans, Buick Terrazas, Toyota Siennas (missed it though

), Uplanders, Montana SV6's, and a Chrysler Town&Country. There was another aisle with big vans, although I didn't read what the actual title was. I just happened to seem them all behind us. So I wouldn't worry about a mini-van. There are OODLES of them there ...
Alamo and National are together ... (well actually separate in E.A., but you can pick from either). We had a Buick Terraza ... forest green, with tan leather seats and a DVD player. It was VERY nice!!! We were VERY happy with it! Just be sure to carry your reservation with you, as the price I printed out and the price that the guy gave me when I returned it had a difference of just over $200!!!!!

So I wasted fifteen minutes in the little kiosk trying to get it straightened out, which the nice fellow did. Thankfully I had that all with me. He couldn't understand why it happened. All he could think was that my pick up time was different than I had booked it as (by about three quarters of an hour), and it may have bumped my special rate or something like that. We were late getting to the airport, but it took us a half hour fiddling around with the darn carseats, finding one that had a proper tether belt in the back with a good enough length to latch it. Once that was over we checked the car through over an hour later than planned ... I dont' know if I buy that or not though ... I'm still a bit annoyed with the whole thing and may just send a letter ....
Good luck ....
Kerri