If I recall correctly, VPI is no longer making the HW-19, so upgrade parts may indeed be hard to come by. As far as alternative tables, particularly the ones you mention, I've heard a cheaper model Michell with an SME arm.
To me there are two basic approaches. One approach is to try to dampen/drain all vibration, particularly the vibration generated by the cartridge itself. These tables are usually massive, and, if they are suspended, the suspension is heavily damped and does not jiggle much when the table is jostled. Some would say the sound of such a table is "dark" or that the background is silent and "black." Critics would say such tables sound dull and too polite. In my system, I like this particular sound because I don't need my table to ADD more zip and liveliness to the sound; such added life is, in my system, more akin to noise and is an annoyance because of its pervasive presence in all recordings.
Other tables, such as the particular Michell table I heard, are on the "lively" side. Typically, they are lighter in construction and have suspensions that are lightly sprung and move easily to the touch. In the right system, that added liveliness can be really addictive and add a whole lot of extra fun to listening. I recently heard, in a friend's system, a Linn table with a Naim ARO arm that sounded dramatically more lively than another table he had (Basis 2500 with Graham Phantom arm). In that particular system, I MIGHT actually prefer the Linn/ARO combination (I say might, because a lot of things that are more exciting and fun do turn to annoying in the long haul).
The VPI is, to me, sort of in the middle. If you are looking for more liveliness, the Michell or Oracle, or a Linn might do the trick. If you are looking for a more "refined" sound (more silent background, more weight, less hashiness) look at Basis, perhaps the SOTA Millenium (good table with a terrific vacuum record "clamp"). I have also heard an SME IV on two Avid tables, the Volvere and the Acutus, and those combinations sounded very good (like the VPI, sort of in the middle between the two types of sound).