Speakers, floor standing or Bookshelfs

More flexibility and (usually) better bass with (at least two high quality) subs.

Stand mount main speakers can image better but the output capability must be sufficient for the size of the room you are trying to fill. Puny stand mounts with subs doesn’t work for me. I would look for main speakers that legitimately cover down to 50 Hz, or a bit lower, so the subs are only covering the bass. It is better if the stand mounts are designed to operate optimally within their given frequency range and do not attempt to cover the lowest octave using their small’ish drivers, which can muck up the bass and the midrange.

As @ghdprentice pointed out, it is also very important to roll the subs in carefully and not run them too high or too loud, as a little less is often just right.

It depends. Room size, room acoustics, and setup are are big factors. The specifics of speakers in question and how they play in your room are more critical than whether they’re floor standers or bookshelf IMO.

Two subs help smooth out room nodes, and you can do more experimentation with placement. Depending on the subs, there are usually lots of options for the low pass crossover frequency, gain, and phase.

I prefer to set the crossover frequency of subs at the lowest setting, run my main flloor standers full range, and set the gain of the sub very low. YMMV, but I hear a lot of subs that have both the gain and the crossover frequency set to high. IMHO it’s best not to feature the subs, but to let them just augment the bass your main speakers put out. Experimentation is the key.

I have been wondering the same.  Got 150W now with two full range towers and a RELT9x.

Room is 12 X 24 roughly 

I been wondering if a couple of Dynaudio Heritage Specials with the REL would be enough.

Image and staging would be the goal.  

They would have to do pretty dang good to best my QUAD-Z4 in place currently. 

I thought about this a good bit a few years ago when I was putting my system together.  My previous couple of systems consisted of floor standing speakers and subwoofers.  I think that what @ghdprentice says above is mostly where I’m at now.  My floor standing speakers have a 3dB down at 32 Hz, so almost full range and they are setup in a room just a bit wider than @jbuhl mentions above.  My REL subwoofers come in at the bottom of their crossover range and add minimally to the overall bottom end.  That said, I eliminated the baby REL, because my goal was to only move air down low and I have two subwoofers (more would be better to even out the bass in a medium/small room).  Recently, Juan of @blisshifi tuned my system/room.  One of the first things that he did was to turn off the subs and to my surprise, what was heard was more musical and with greater clarity.  Yup, my subs volume was set too high.  I thought the crossover was set at the lowest point, but that might not have been the case.  When Juan was done, there was a benefit to the subs, but it was more subtle and they weren’t destroying the lower octaves produced by the main speakers.As an aside, Juan suggested that more subwoofers might be beneficial in my smallish medium size room.  When it is all said and done, might I have been better to take the extra money spent on subs and gone with a better speaker?  I don’t know, but it was something that I did not consider because I tried to keep cost down at each stage, without looking at the money I would be spending at the back end of the buying process.

Thanks you all of you for the input. My room is a medium L shape where I always have to play with toeing the speakers due to one of the speakers having to be placed into the bottom part of the "L" wall to avoid as much reflections from the wall in front of it.

I gather that bookshelf speakers (on stands) would present a little more challenging task with imaging/capacity to fill the room.

So, For me, to keep full range speakers, plus two subs seems to be the best option.