Experimenting with Speaker Room Placement

So you pulled the speakers out 5 feet and noticed better "clarity."  I assume that means the bass was less boomy and the sound was better balanced overall?  What is telling you side reflections are still a problem?  How far are the speakers from the side walls and how much are they toed in?  These two variables alone could go a long way to fix sidewall reflections if indeed they are causing a problem (see below for more).  What areas still don't sound right and what are you still looking to improve?  The more detail you give, the better advice you'll get here. 

As as far as going to bipolar or omni-directional speakers to deal with room issues, this seems a bit extreme IMHO. First you need to see if that type of sound, which is different from direct radiating speakers, even appeals to you.  As others have mentioned my our room does not sound overly problematic as it's very similar to mine and others here, so you should be fine with a little more help and effort. 

BTW, to find sidewall first reflection points and treat them, sit in the listening chair and have someone stand with a mirror against the sidewall near the left speaker.  Have them face the mirror directly toward the opposite (right) wall and walk directly along the left wall toward you, and when you see the left speaker in the mirror that is your first reflection point of the left speaker that you can mark with painters tape or whatever.  Keep moving mirror closer to you from that point and when you see the right speaker that'll be the first reflection point of that speaker on the left wall.  Repeat same thing from the right wall.  Try temporarily hanging a piece of carpet in those locations to see how it helps (or you can put something like a bookcase there as long as it's high enough).  You can follow the same procedure to identify first reflections from the ceiling and floor as well, which are also important areas to identify and potentially treat (a carpet or area rug usually takes care of the floor -- ceiling's a bit tougher aesthetically speaking). 

Again, I find long wall vs. short wall is very much a personal preference thing (assuming your room and speakers can work both ways) and you'll probably find yourself finding one or the other more personally satisfying pretty easily between sonics and how close you want to sit to your speakers.   FWIW...

Nearfield or not, short wall or not can largely be personal preference, but it can also can be somewhat dictated by your equipment -- most of all speakers.  For instance, tower speakers often require a greater listening distance so their drivers, which can be spaced farther apart, have enough space to come together -- not as much of an issue with something like 2-way monitors. 

Personally, I'd put the speakers along the short wall if possible as you can listen in the nearfield or not, and you'll have more freedom to pull your speakers out further into the room (also need to give them some space from the side walls).  This not only helps improve soundstage depth but can also help mitigate bass overload, which may be what you're experiencing.  If you haven't already done so, try pulling your speakers -- especially the towers -- 3, 4, or even 5 feet out from the wall and you should notice a significant improvement in tonal balance along with possibly a greater sense of a 3D soundstage.  It may also help your speakers disappear more as a sound source as you get them further away from reflective boundaries.  Before I had a dedicated listening room I used to pull my speakers out for serious listening and put them back to avoid divorce.  Some things are just worth the effort. 

Other things you can try are toeing the speakers in more toward the listening position or plugging the port if the speakers have them (although this doesn't work well with many speakers).  If you're on a suspended wood floor you can also try getting some marble or concrete slabs (and/or audio oriented footers although these can get more expensive than slabs) under your speakers to help decouple them from the floor.  Also, don't place the listening seat directly up against a wall as the reflected sound can muddy things up considerably -- even a few inches can make a big difference. 

I'd think with your size room this should be a manageable situation to a good degree even without room treatments if you have placement flexibility.  That said, I don't know of a room that wouldn't benefit significantly from the use of some well-placed treatments (assuming no electronic room/speaker correction is being used), so that should eventually be a part of your plan regardless.

Just some thoughts off the top of my head but hope some of it helps, and best of luck.