Hightower has very little prgression, but you'll notice that the hightowers themselves are mostly metal, even the red one, which is right next to a largely red wood building. Even just setting the hole and ramp in concrete would look nice.
Thundermountain's final, (which i personally feel works better considered as its own map) is entirely wood. To an EXTENT, i think it sort of works, since the tower is a dramatic landmark in itself. However, with, say, goldrush, setting the final building in wood wouldn't work, cos the finale is dull as distcahwater, shape-wise.
Frostfell NEEDS this visual cue, because the finale is, well, a ramp and a hole.