Do you use spikes for tile/marbel floor?

I have hard tile over concrete flooring, with the BBC MK-2 gold plated brass cones (available from May Audio Marketing) which come in nice boxed sets including the little saucer protectors for the floor. These have a nice low profile & even have threaded adjusters with locking nuts so you can snug them down tight even on somewhat uneven surfaces. They claim that the protecton saucers actually enhance coupling vs. degrading it. The cost is quite reasonable & the sonic improvement is indeed significant.
I've heard of coins being used as floor protectors but the spike eventually drills its way right through. Vibrapods have also been reported to work well under speakers although the sonic signature surely must be much different than with spikes; it might be worthwhile comparing.

I'm using Symposium Svelte speaker platforms under my Hales T8's. They are on tile and do a great job of coupling the speaker to the floor.

4 pennies per speaker. This is the way to go.
Cheap and doesn't muck up the hardwood floor.

I have my spikes replaced with standard furniture glides from the hardware store. Meadowlark recommends this for their Kestrals, might work with your speakers as well. The thread size is common, 1/4 20. If this doesn't work Linn makes a product called "Skeets", hard metal discs with holes in the center for spikes. Hope this helps.

It depends. My Martin Logans prefer brass spikes into brass cups and my Thiels prefer thin nylon washers.