Everything I've read so far leads me to believe that suspended tables are more forgiving of vibrations in the room. Is that not so? Like I said, my floor is not a concrete slab. Now I am confused.
It all depends on the design solution for each approach, the suspended design and the high-mass non-suspended design.
Turntables from Avid, Basis Audio, Michell, etc. have efficient design principle/implementation and floor vibration should not pose a big problem for their designs. That means that you probably don't need to invest on a platform to go under the table, although my experience with suspended turntables is that a well designed platform always helps.
In a high-mass design, vibrations are mostly absorbed by the mass itself. This doesn't mean that all high-mass turntables are good at deadening resonance. The materials and their dampening characteristics have to be carefully chosen.
I personally don't feel confident saying that high-mass non-suspended designs are better with vibrations than suspended ones, or viceversa. It will always depend on the particular design.
I had a suspended turntable a few years ago, which I always felt it was lite in the bass area. I changed my whole analogue rig for a high-mass non-suspended turntable and I'm getting great bass, mid-range and highs, all with great stability. But because I changed the entire setup, including tonearm, cartridge and phono preamp all at once, I cannot say for sure that the suspended turntable alone was responsible for the lite bass.
There are great turntables on either side of gamut, so you should look at all the features that a particular turntable has to offer. IMO, speed stability is extremely important, so I recommend you look at a turntable that has a motor controller with speed adjustments.
Best,
iSanchez