If your problem is a floor that moves when you walk, get yourself a turntable wall-mount. Because you have a VPI Signature 21, I'd recommend going to a local shop that does metal fabrication and have one made for you. Those VPI tables are very heavy.
You'll need to get a handyman to attach it to your wall with lag screws into studs. This will need to be an extremely sturdy platform due to the weight of your table. Keeping in mind that this is a $10k table with a cartridge to match, spending a few hundred bucks shouldn't be a big deal. You want to get this right.
A wall mount completely isolates you from anything your floor is doing.
Turntable Isolation
Im looking for an isolation base for my VPI Signature 21. My listening room is over my garage and a times my footfalls cause the table to skip. What have you used that works?