I've been using X-Plane quite alot recently, but am waiting patiently for v5. Something that the team should address is your descent profile. It would be lovely if you didn't get the same 11k/12k crossing restrictions every time. Since you asked for suggestions, mine is to make the descent profile a little less predictable, for example based on the amount of AI. And what about using FS's (albeit static) airspace data to set sector lateral and vertical boundaries, like this http://www.x-plane.com/blog/2011/02/the-world-is-under-control/

crossing restrictions are repetitive, and boring for a reason. can you imagine a approach controller having a dozen planes coming at him at 12 different altitudes, crossing into his airspace, that he will have to manage - because the last center controller was feeling a little crazy that day. nope, you don't want excitement in atc. boring is good. excitement leads to mistakes. jd

In the real world airlines are asking for constant descent profiles and some have been tested. This would place aircraft at many altitudes as they enter local control. Many airport ATC managers have objected because of the increased workload and possible safety compromise in trying to separate aircraft keeping a virtual snapshot in controller's minds when trying to separate both vertical and horizontal positions with aircraft scattered about. I've read r/w articles about the workings of ATC. Local control of an airport tells center what altitude they expect for the transition window of enroute to approach and center obliges. This is especially important in areas of congested airports where by arrival sector vertical positions are established for each airport providing vertical separation between airport traffic patterns. (RC provides two crossing restrictions based on nearside/farside approaches which simulates this to some degree as far as arrival sector goes.) The FAA for testing left the decision of allowing constant descent approaches in certain areas up to the local airport ATC managers at my last check which they based on controller workload. So, in answer to your question, the majority of local control areas want all of their 'duck's in a row' wanting entrance to their pattern at local control assigned altitudes.