Little two-way boxes on a stand....

Try Alta Celesta's. They wear tailored by Armani.

My older Sonus Farber Concertos have clothes in my current set-up. 

Add a sub and they sound just as big as a floor stander.

I think it very much depends on what type of music you prefer.  I don't find them satisfying on any type of large scale music.  Orchestral or rock sound very weak and a sub doesn't solve the problem.  This type of music requires a large woofer that plays above the subwoofer frequency range to sound right.  A small woofer can't provide a realistic punch.  I think you need at least 8" and 10 or 12 is better.

On the other hand, if you listen to smaller scale music, I think small monitors and a sub are fine.  I find them nearly indistinguishable.

Add a sub and they sound just as big as a floor stander.

This is pretty much what I have found. 

I have some incredible DIY (with close to state of the art drivers and x-over), sitting on a woofer module, and they sound as big as any 3 way floor standing speaker. 

Now mind you, the woofer module is NOT a subwoofer, it is a true woofer. The 2-ways are being crossed over at 200 hz, and the 10" woofer module takes over from there.