building at 320 West 86th Street

giddyup2: I've posted several times about 310/320. Here's a search that should link you to the relevant threads:
http://streeteasy.com/nyc/talk/search?search=royal+summit&commit=Search

One problem at 310/320 is that it hasn't been feasible to consolidate the lobbies. That means a fairly small number of units has to bear the expense of manning two entrances. You see the result in the maintenance. (At the third sibling, 302 W86, maintenance is a bit less punishing, and 302 has reaped some financial benefits from the deep pockets next door at 535WEA.) I'm also not wild about those narrow, mid-block, floor-through layouts; that's a matter of taste. I do like the block: You get the light of an avenue, without the traffic.

I would say 610 is a more gracious building, and has some wonderful apartments. #3D clearly isn't the best 610 has to offer. In fact, it shares some weaknesses of the floor plans at 310/320 W86.