If you are renting from MCO, they do not have a Standard aisle, you just pick from the Full Size aisle.
Twice over the past 2 or 3 years we have actually picked a Buick Verano from the FS aisle and noticed that Alamo lists this as a "Standard" Vehicle. We did notice the Chrysler 200's on the aisle also, presume they were "Standard" also.
Recently we saw Hyundai Sonata, Toyota Camry (definitely Toyota, pretty sure it was a Camry), a Van and I can't swear to it, but I think I may have seen a pickup truck. Definitely saw a Dodge Charger.