Hi Ron,
I've had hardwood floors for about 8 years now. At first, I determined the best positon with the gliders and then spiked the speaker directly into the floor. Major increase in performance on all levels.
Rich came and visited last summer. He suggested that I buy something to decouple the speaker from the floor since the bass output of the Summits was definitely sending vibrations through the wood floor system.
You can check out the Music Direct website for many iterations of this type of product but I ended up purchasing the BDR "wide pits". The spikes simply rest inside the dimple of the device.
They do a phenomenal job of isolating the speaker from the floor resulting in another substantial gain in clarity, speed, soundstaging, and mid / low bass definition.
Only down side is that they are a bit pricey ($82 +/- per each) but to me, worth every penny.
The other plus is that Music Direct offers a 30 day money back so you can audition and judge for yourself. However, I strongly recommend that you get the Summits broken in and in the right place before you go this route.
Good luck and happy listening.
GG