Suggestions for Full Range Speakers up to 10K

Hi Everyone,
I am new here and I am working on a home theater/2 channel combined living room setup.  My room is shared with a kitchen (island counter separates kitchen from living room).  My original plan was to convert my 2 car garage into a home theater as I have a walk in cooler there with 5 beer taps through the wall. My wife is not fond of the garage idea, but I think I could convince her to do a full 2 channel setup out there and leave the HT setup in the living room where it is now.  But in the meantime, I'll continue getting the living room dialed in.

My setup is as follows:

Marantz AV7704 pre
Marantz MM8807 amp - currently pushing my center channel, sides and rears. No height speakers at this time.
Peachtree Nova300 - currently doing double duty pushing floor standing fronts using HTB for the HT usage.  I understand this is not the highest end, but you have to start somewhere, and it actually sounds pretty nice, even if the buttons are flimsy-ish.

Fronts are ML Motion 40's, center is ML Motion 30, sides and rears are older Aperion bookshelves that I plan to upgrade down the road, but they are sounding ok for these duties for the time being. I like the combination of the 40's with the Nova300, as I run though the DAC into this amp via USB-B in from a Mac with all my FLAC files on it. Sounds decent to my ears and is more than loud enough but I think the mid and low end needs a bit more presence though. 

Room is 16' x 24' but opens into a kitchen and has a hallway leading to the back part of the house where bedrooms are. My main wall with my projector screen on it and all my components is about 12 feet wide as I have a desk in the corner and a kitchen counter on the opposite side.  Ceilings are beamed, and I have multiple bay windows that are covered with shades.  I would say the room is harder than softer with respect to sound reflection versus absorption.

My thinking is to add a full range speaker in the spaces between the center channel and Motion 40's, which is about 22" of space to work with, up to 46" tall (bottom of my screen) and 30" deep. I was originally considering a pair of subs in this space, but having them able to do double duty for music and HT seems more difficult to deal with as most subs have the controls on the back and I don't feel like reaching back there every time I want to go between HT and 2 channel work.  And frankly a good set of full range speakers shouldn't need a sub for 2 channel work. I think I will do one big sub later for HT use only, but I'd rather focus on the 2 channel part first. Another option is to replace the Motion 40's with a fuller sounding speaker altogether, but I figured since I have the extra room from the MM8077, I can push the Motion 40's from that amp and move over to a fuller sounding full range for my 2 channel application. 

I'd love to hear some expert opinions on what speakers would make sense for my application.

Thanks in advance.