Since you have a HT room already, if you want earth shattering explosions you will watch it in there. I think for you living room you are looking for a nice alternative to TV speakers.
I think you might consider a pair of M2's (or 22's) and an EP175. I had a 175 for a few weeks and thought it was a great sub for music and still had some horsepower for the odd dinosaur footstep or thunder clap!
THe M2's are very small, easy to place, and I have heard great things about them. Plus the imaging is so wonderful that I doubt you would miss a center channel.
In my living room I have a pair of Axiom AX2's from a past life and they are perfect for background music, or basic TV watching.
