If you are going to sit nearfeild (3-4 feet) ,then you need to get a speaker with the mid-range and tweeter that are in very close proximity. A small 2 way with truncated midbass and treble frames is ideal - it will have very similar response close and far away. A 2 way well built monitor is usually superior to a floor standing model - as the 2 way will have far less cabinet surface area to resonate (a serious issue that reduces sound quality - and one of the biggest things allowing planar/esl speakers to have such high resolution sound - they typically lack most of the traditional cabinet - so it can't resonate in the first place). You are best to use dual high quality subwoofers, combined to the monitors using an active crossover, and this will give you the same perfect seemless integration as a 3 way floor speaker, but with less cabinet resonance and likely higher fidelity bass (as you do not usually find the same quality/capability woofers in a full range tower as compared to dedicated powered subs of decent quality). You do need to have seperate pre-amp, or a stereo receiver with direct AMP IN/PREAMP OUT feeds in the back that are shorted with a shorting bar, in order to properly use a high quality external active crossover. Note: a high quality active xover need not be expensive. Behringer makes a model for $90 that uses extremely high quality components, power supply, switches and potentiometers, and will provide transparent operation for any level of sound system. It has infinite variable frequency settings with 4th order L-R filter slopes. More advanced DSP models can allow you to gain higher sound quality by being able to compensate for some room low frequency response errors and being able to make subtle and precision response changes to your monitors.
-Chris