Heavy difficult to move speakers- how do you deal?

Hire movers.

+1 Furniture sliders with adhesive attached to the bottom of the discs holding the spikes. This has made it easy to adjust the position of my 100+ pound towers.

This thread has officially been done to death. Enough.

Really terrific ideas.

Speaks to a serious need for speaker manufactures to consider what people are having to go through and offer solutions in line with how they've created their speaker feet.

Townshend Audio Seismic Podiums do an amazing job of cutting the transmission of vibration between speakers, floor and your system. Difference in my system compared to casters was startling (200+ lb speakers).

Because the isolating springs are in housings above the rubber feet you can put sliders under the feet with no harm to sound quality.