Cheap tweaks...What would YOU reccomend?

Try wood damping on the face-to-face Tibetan bowls that you use between your speakers.

The SQ Isol-pads are a simple and affordable way to isolate components. have used them with speakers on hardwood floors(also on indoor/outdoor low pile carpet).
They have been recommended by both Stereophile and the Absolute Sond.

Inner Tubes are a joke. Here are ones that do work.
1)Speaker placement. For example with a 12 X 12 room place the listening chair/couch 3' for rear with speaker 3' from side walls and 2 1/2 from rear. Use this formula and toe in 3 imches. It will work. Spike and and all speakers and subs.
2) subs sound better up front on one side or the other cross firing edge of woofer parallel with edge of front speaker
3) Do not put sub or speakers in a corner
4)soft pucks helps cd players and transports
5)get a dedicated audio stand -fill with play sand
6)let equipment warm up stabilize before listening at least 30 minutes

Get rid of your wife...

By far, the best isolation devices I've ever experienced are simple fiber scratch pads. They come in varying thickness and stiffness. They are almost 100% immune to vibration. I say "almost" because nothing is perfect. But when you put your hand on the component they're under, there's no detectable vibration whatsoever. They seem to be acoustically dead. They are awesome under a turntable.