Another option is the KEF Q100. It is front ported and comes with a bracket for wall mounting - $400 a pair at accessories4less. The matching center, the Q200c, is $329 so that would put the total at $1129. Or you can look for a single, fifth Q100 to use as a center (they are concentric drivers so you can lay them on their side as a center). I mention the KEF's because they will put out more sound (without losing their composure) than the NHT, and you have a somewhat large space.
Another option is the Ascend HTM-200. It is sealed and wall mountable - $770 for five speakers. They have a very nice sound, but, like the NHT, I'm not sure how well they can fill that room.
A lot depends on your listening habits. If your listening is at moderate volumes then some of the wall-mountable speakers should work fine.