Does a sub need to be on the floor?

Most important question buddy what price range ? You can spend 10k in stand monitors . Whats your budget and electronics budget 

/erik_squires im liking you more and more reading your post .. 
I'm by no means a headphone fan but sometimes choosing the lesser of two evils may be key . 
     Inna same to you i think we are on the same path in our thought path

   Op . I would personally hesitate putting a sub somewhere that is not somewhat stable it will resinate and you will battle that demon imo .. Put the sub on a worthy platform or audiopoint or stillpoints but all these seem bassackwards get a good pair of spkrs buddy start there subs come later imo .. 
Respect 

Acoustic zen adagio jr .. Zu .. Too jmho 

Jl 110 are my top choice under 5k each  killer 

Spend your max budget on your spkrs. Then match the electronics to them get the subs later jmho

It's all Apples and  oranges op 
jl are above what your shooting for imo no offense 
.. Everyone has opinions but if your buying spkrs and are keeping for sure ! Lol your power buy spkrs suited .. If not be careful and buy the best sounding spkr you can afford . Probably a relatively sensitive spkr and buy a amp intergrated probly that will mate well . Or your pocket will be open for a long time . The 2-3 k spkr range is wide open there are some great spkrs in that range . If you go used ( my reccommended choice) your in the 4-6 k new range which is just another level. A 2-5 k monitor with a real stand will sound great if mated well . Your in floorstander money then too.. Spend a cple g used, cple g used on a sweet intergrated (or a surround amp) which in general youll pull your hair out researching a good surround amp lol . . Look at kef acoustic zen splendor go listen to some and mate it properly you will be glad you did . In your range a used sunfire hvs or rythmic is easily obtained for like 500-800 bks
good luck  

stan those are audiopoints i run all of roberts stuff myself all the way thru...thumbs up