bookshelf or floorstander

I've been researching bookshelf speakers for a while now. Originally I wanted them because of the space I projected putting them in... but now it doesn't matter if I have a bookshelf or a floorstander.

What are, if any, the sound advantages in a bookshelf speaker versus a floorstander and visa-versa? I mean, I know a floorstander will have more extended bass and placement may be easier with a bookshelf... but besides this, what about soundstage, etc...?

BTW, my listening room is about 12'x15'.
12x15 is good for bookshelf and smaller floorstanders as long as you do not want to have the concert levels and dynamics?! You can get great imaging with a cool bookshelf(Dynaudio,SF,Spendor) but you will get a better bass and solidity?! with something as Living Voice or SF Cremona...
The Voice and SF Cremona you mentioned are floorstanders I'm assuming?

I value imaging far more than bass response... sounds like bookshelf speakers are the way to go for me.

Thanks Prcinka.
Regarding midrange, upper end, and imaging, you get more, dollar for dollar with a book shelf than you do with a floor stander. With the book shelf, you aren't paying for the extra cabinet that goes to the floor, or the design of the bass portion of the speaker.

If you value imaging far more than bass response, I would definitely audition book shelf speakers before floor standers.
No reason in the world to get bookshelf speakers when you factor in the cost of good stands. Put the money you would spend on stands on your floor standing speaker purchase and I am sure you will wind up with more speaker, literally and sonically.
one of the British hi-fi mags tested the main monitor vs. the equivalent floorstander within the same line among 4 or 5 different speaker manufacturers (e.g., Quad 11L monitor vs. Qud 21L floorstander). The exact lines/models tested escape my memory, but the article concluded that the monitors delivered better overall performance. I think that at the price point tested (not megabucks), the floorstanders produced more bass, but lower quality (i.e., flabbier) bass.
A negative with floorstanding speakers is the cost of the cabinet. That cost can detract from the budget that can be used for the drivers and crossover parts.

A larger cabinet will be more likely to have audible resonances than a smaller cabinet as in a stand mount speaker.

A floorstanding speaker may be marketed as being full range, when in reality many are not.

A floorstanding speaker does not allow the bass and mid/treble to be physically decoupled. The placement of a speaker for good imaging is not likely to be a good placement for smooth bass response.

So in my book, 2.1 systems have a theoretical advantage that can be easily realized in practice.
Good to hear. Thanks for the responses.

Ya, I heard that about 30% of what we hear coming from a typical speaker is from cabinet resonance... which would make sense that this would give bookshelf speakers a clear advantage just based on the simple principle that the sound waves have less room and surface are to bounce around and collide with eachother on.
Get floor standers...youll always be wondering if...if only i would of got floor standers.(imho)did the same thing.
I'm going through the same process right now (see my threads on the subject of which speakers to try), and it seems that placing a high emphasis on soundstage is channeling the recommendations in favor of nearfield monitors. Right now I have floorstanders (Linn Ninkas) and they're plenty agile without any noticeable box resonance, but they don't through quite as convincing a stage as I'd like.

This having been said, the best soundstage I ever heard in my whole life was from a pair of Hales Signature IIs, which might also be the largest (and most expensive) speakers I've ever personally auditioned. So I'm not sure that the hard and fast rules about all of this are quite so hard or fast as they may seem.
Something else to consider.

I have Totem Mani-2 monitors that do a good job of bass in a smallish room. In my large living room, though, the bass isn't quite there. I do focus more on what's there and not what's missing (extended bass).

What's nice about this is that you can listen to different kinds of music without worry of big volumes of bass upsetting neighbors, wife, or anyone else around. Bass has a tendency to make it's way through the house more.
Ya. I'm in a fairly small listening room as well... somewhere around 12'x15'.

Another factor is finances... to drive a passive subwoofer in a floorstander, you would want to have plenty of clean power... which costs more money. I, on the otherhand, would rather have an efficient bookshelf that I can drive with a clean 50wpc without a problem.
My room is exactly 12x15 and I just sold my VS VR-4SRmk2 in favor of a 2-way stand mounted monitor. The VS sounded great, but I had to load up my room with massive bass traps to control the low end. Even then, I wasn't getting the best sound I knew could get. In a samll room, you get a much better soundstage when listening to nearfields. If you listen to rap and dance music, then floorstanders will give you more of what you want (bigger low end), but in the big scheme of things (and in my opinion), a GOOD monitor speaker will sound better, and still have plenty of low end for your small room. My monitors go down to 30hz.