I am no expert by any means (quite novice, and pretty dumb when it comes to this stuff, as others can probably attest), but speaking as someone who has a room similar in size to yours (mine is 8' x about 16'): Having those huge towers along with 2 Subs does seem a bit excessive to me for such a small room, so I would probably go with (if I had all the money in the world) a pair of bookshelf front L/R's (RP-600 or 500M's), probably a slightly smaller centre (RP-600C or RP-500C so as to match the front L/R's), a smaller pair of bookshelf speakers as my surrounds (R-51M's), and likely would be fine with RP-140SA's as front heights. I would probably also only have one Sub.
But I'm also not you, so take what I say with a massive grain of salt. I can't imagine needing massive speakers screaming at me when I'd be maybe ~3-4 feet away since the room is only 6 feet wide, especially if I sat parallel against one of the longer walls as there wouldn't be much room in front of you. I can't even fit a coffee table in my room, and it's 2 feet wider than yours. I sit parallel along a longer wall in my room, all of my speakers are 5.5-6.5 feet away (sub is about 8 feet), and it really doesn't take much volume to feel the full, enveloping effects of the system I have, which right now is:
Front L/R - Polk RTi A1's (A3's are just too big for the shelf everything sits on)
Centre - Polk CSi A4
Surround L/R - Onkyo HTiB's (which I will be swapping out for a pair of Klipsch R-14M's very soon)
Sub - Polk PSW10 (which I also hope to swap out by year's end, possibly with a Polk HTS 10")
I may or may not move those Onkyo HTiB's to a Front L/R Height position for a 5.1.2 set up.