In ceiling surrounds/ upgrades?

I am setting up a 5.1 surround system. Currently have: thiel 3.6 mains, cs4 center, JL audio fathom f112, bryston 4b and rotel 5 ch amp, passive stereo pre amp and an outlaw audio processor. Currently only using 2 ch stereo st up. I am more interested in listening to music but want a good surround system. I am planning on upgrading to a surround pre pro. The room is 25 ft x 13 ft and opens into the kitchen/ dinning rm. My next purchase will be the surround speakers. The couch is tight against the back 13 ft wide wall facing the tv mounted on the front wall 25 ft away. The room acoustics are poor and needs help. I was thinking about going in ceiling surrounds (thiel 1.2 hiplanes?) directly above the listening/ viewing couch, but am concerned with placement/ sound optimization. Any opinions on best surrounds option? Also any other upgrade recommendations on equipment or on how to get started to improve room acoustics ? Thanks in advance.

Not sure I correctly understand your comment about "directly above" the listening position. If you mean directly over your head, that may not work to well. If you have room left and right (which you infer your do) then that would work much better. Could you clarify a bit better for me about your surrounds? If you can get the surrounds about 9 feet from the listening position that should be OK. That's the setup I have, however I don't have an immediate back wall boundary like you do.
Thanks for your response. I have an L shaped sectional sofa against the back wall that takes up the whole back wall and part of the side wall. The in ceiling surrounds would go above the sofa along the back wall. My concern is the speaker placement directly above the sofa. The other option is to place the surrounds forward of the sofa area. Any thoughts: 1) if the in ceiling surrounds are the best options for my layout; 2) is placing in ceilings in front of the listening area a sonic mistake?; is it worth spending the money on the in ceiling Thiels vs cheaper in ceiling surrounds?