Should I bi-amp or bridge my amps to feed my speakers

I would not bridge your amps.  It forces two different output transformers to work in series. 

Bi-amp vertically...it should help with separation and soundstage. Add an active subwoofer to handle only the bottom octave. Set the low pass crossover on the sub at it’s lowest frequency, and set the gain so that you can barely even notice the sub.

You bridge your amps and you create a public address system from a stereo system.  It will be louder and it will sound poor.  If you want to bi-amp, that will likely yield better results.  Speaking from experience here.

I have heard those speakers with and without subs at a dealer in Portland and the spatial difference was not subtle. They were also spread farther apart from each other than "normal" and severely toed in. I don't remember which amps were driving them but I'm sure there was more power than the 35 wpc you are using.

I have heard those speakers with and without subs at a dealer in Portland and the spatial difference was not subtle. They were also spread farther apart from each other than "normal" and severely toed in. I don't remember which amps were driving them but I'm sure there was more power than the 35 wpc you are using.

I am not sure that we know that for sure…

The amount of power in the 20–80 Hz region depends on the music, and the system with the subwoofer May have been <35 wpc, and the sub well over 100 watts.

We sort of don’t know, but it is possible to significantly lower the amount of power by adding the sub.

@aewarren 
Can you further describe the “not subtle” difference?