I've got lots of experience in the worst places for seeing, if you'd like to tackle it by elimination. Mountainous areas are bad, unless you can punch through to the tops of isolated high peaks (a la Mauna Kea). Prevailing winds are broken up and funneled, there is altitudinal flow of cool air down the valleys at night, and differential heating of mountainsides causes a barrel flow (thermals, used by paragliders etc). Mix that up and you get chronic poor seeing. I occasionally go to flatter areas to observe like Snake Valley - people there might say, "oh, the seeing is off tonight", but for me it always seems brilliant compared to my mountain valley location.
Your mention of the Snowy Mountains is interesting though Greg because there are fairly extensive areas of high plateau. I've often wondered myself what it might be like in places there (apart from very cold!). Less air to see through (and therefore less air available to be disturbed) sounds good, but I suppose it would come down to whether the constricted air flow over the top has time to 'settle down' into an even flow.
Be very interested to hear from members who have observed there.
Cheers -