The four buildings in Congress Park, opening May through August, are pretty much identical. All are about the same distance from the bus stop, main pool, food court, etc. The two middle buildings flank the leisure pool, so perhaps that is of some interest to you.
That said, recent reports indicate that a fifth building may open in October. That building will be in The Springs neighborhood, and will be a couple minutes closer to the main pool. However, The Springs will not have any direct view of Downtown Disney.
Depending on your interst level, you may want to specifically request either Congress Park or The Springs.
Also, there are two different types of Two-Bedroom accommodations--dedicated 2Bs and lockoffs. The dedicated 2Bs have two queen beds in the second bedroom. The lockoffs have one queen and a sofabed.
The lockoff / dedicated designation is supposed to be guaranteed at the time of booking, even if it isn't noted on your confirmation. Depending on the number of people you need to sleep in your room, you might want to specify the type of 2B that will best suit your needs.
