Room setup...diagonal or standard and how to treat

Hello, I have a room that is 14 X 16 with 8' ceilings. I use Dynaudio C1 speakers and Mac and Esoteric gear on a 5 shelf rack, sitting beside a 36" TV. This is a room for both myself and my family. Here's the dilemma....in this 14 X 16' half of one of the 16' walls opens into the dining room and there is also a doorway along the rt rear of the 14' wall.

_______________________________________
! 14' (a) >> !
dedicated !
opening to lines !
dining rm. !
<< \
!
16'(a) ! 16'(b)
!
! !
! / 8' ceilings
! !
! !
! !
! doorway !
!____________14'(b)__________ _!

My question is....what is the best way to set up my system. Diagonal? Along the 14' wall (a) to take advantage of the dedicated lines placement? I seem to have lost bass and brought more upper detail to my soundstage when I recently tried diagonal facing out from the dedicated lines corner. The opening to the dining room is a problem I assume and wonder how best to minimize its effect. Lastly, what type of room treatment would you use and where after there's a concensus on the room setup. Thank you all for your generous time.