Just to throw in an opinion which will be heresy to many people...
I have a B&W speaker system - XT4 floorstanding fronts, XT2 bookshelf rears, XTC centre and PV1 subwoofer. In spite of advice to the contrary, this is set up with no bass management in my Arcam system - all 5 speakers are getting a full-range signal, and the crossover is set as high as possible so the PV1 gets as much signal as possible. (This is not what B&W advise with this system - they suggest a 60Hz crossover frequency, with signals above this going to the speakers, and below this going to the sub.)
That said, I much prefer the sound of my speakers with the bass management doing nothing. It isn't as stupid an idea as you might think - the response of any speaker rolls off gradually outside the range in which it works, so the fact that I am sending full-range signals to the speakers means that I simply won't hear the bits that they can't reproduce. Bit it also means that I have no signal processing applied in the amplifier, and to me, this produces a sound I prefer - in effect, instead of applying digital filtering in the amp, I am allowing the speakers to do the filtering for me.
The reason for all the above waffle is this - even if you have a sub, I recommend getting floorstanding front speakers. The less bass management you have in the system, the better stereo music sounds (IMHO), so front speakers with good bass extension are worth having.
As I said, the above is my personal heretical viewpoint, but for me it sounds better like this, so I would strongly recommend going for floorstanders at the front and moving your bookshelf speakers to the rear.