Material Selection for Vibration Damping

OK, physics stars: it's your time to rock!

I'm putting together a turntable stand and have heard the remarkable advantages of vibration isolation; I'm sold on it.

I'm considering a laboratory isolation table to go under my Vibraplane and wonder what experience you have had with material selection, testing or a manufacturer's stand-out solution.

What among the commercially available options makes the best platform for a Vibraplane?

Acrylic? Marble? Steel? Wood? Concrete? Multiple layers of MDF? A specific type, source or combination of these? Something completely different?

Clearly mass is only part of the equation because resonance frequency is also determinative of playback quality.

What would be an ideal setup? constrained layers interleaved with isolation material, like rubber, sorbothane, or fabric? No layers?

The floor is open. I look forward to learning what you have discovered over the years.

Thanks ahead of time for sharing your experience. And Happy Solstice Season, with wishes for a wonderful turning from 2011 to 2012,

Aside from upgrading to a Minus K or Halcyonics platform, what is it you wish to gain from changing the stand beneath your Vibraplane? While I'm not dismissing the possible sonic changes in regard to a stand, from an isolation standpoint, you're only a rung or two from doing the best you can (within reason). My criteria for a stand would have to based upon what type of material the listening room floor is constructed of, but a general recommendation would be rigidity, lack of obvious resonances, adjustability (for leveling purposes), and aesthetic appeal.
Birch plywood, 1.75" resting upon silicon gel footers is the best I have heard. Something about the resident frequencies in the audible range being absorbed into the wood. The fact that it is made from millions of interlocking one of a kind shapes/fibers allows vibrations and sound to be dispersed automatically as heat and will not be transferred again to other areas within the system. Quite a cure for what ails you.
No time to fool around, go with the best. What is the best? An electron microscope platform. Yes, pricy, but some can be had for about $10K. The fall back would be 'moon gel', a drummers accessory sound for about $6. So, hurry to the Musican's Friend store and see if 'cheap' will work.