Well, why don't we try something completely different? Just because it has the phrase 'mountain' in it doesn't mean that it is automatically a roller coaster, I mean I'm sure we could use another ride system, or even create our own..What a drop system? Here, Disney has this nice, patented motor that they created for ToT, and they haven't utilized it since Tot was built! I'm Seeing A Spiderman type ride here...Going through animal Habitats..Not a huge amount, Polar Bears, penguins, and seals, just three exhibits..You'd be travelling in a modified 'Snow Mobile' That would take you on a tour of this area...After the exhibits, and avalnche would occur, and your car would careen through falling rocks and such, and 'splash' into fake water (provided through 3-D screens) until the car pulls into an elevator system exactly like ToT..Your Snow Mobile seems to have entered a cave plagued with some thermal vents..Now, your Vehicle is throwin into the air, and dropped, multiple times due to the gas eruptions, The vehicle starts beeping and going crazy because of systems failures (The great part is that the vehicles ability to pitch and rock while on the elevator mechanism will not be compromised, so it will feel like you are being thrown into the air because your vehicle will nto be staticlly erect, it will wobble and move) But of course, you land into water (again, not real water, projected) Complete with a jet of real water spraying into the cabin....
Because this is somewhat of scary ride, the animals will also be able to be viewed from a new 'path' that will snake through the mountain, or perhaps, a more gentle 'Glacier tour' could be thought up, perhaps a boat ride? Complete with singing and dancing penguins? I dunno, I think it sounds fun.
Also, This land is going to be hard to make. It cannot be visible from any other area in the park, because the white, snowy peaks will ruin the steamy, hot jungle theme of the rest of the park..Chose it's location wisely, and consider 'sinking' this area down into the ground somewhat.
Also, have you considered what else you'd have in this land? Antartica is, pretty much, roped off from civilization, it has a few research stations on it, but no major cities or anything. Perhaps if we palced it in Alaska, and recreated Nome? Then we could tie in some Eskimo and Inuits heritage into the buildings....Sorry this was quite a bit of rambling.... Bleh..