[Kuruharan]

I would say that for a 6' elf, it would be considered leaping for him to implant the spike of his helmet into a 15' balrog's chest. (Even though I still think that 15' is a bit much, but I'll go with it for a minute, it's better than 50').
One of the things that I hear over and over again when I'm having this argument is the line where, "The Balrog drew itself up to a great height." I think that this is where the idea for huge balrogs comes from. But I don't think that "great height" implies the size of an airliner. Certainly, when compared to the size of the hall 15' probably does not seem like a "great height." However, lets remember who the balrog was confronting. Gandalf was not extraordinarily tall. To somebody who is 5'8"-6' (just for instance, I don't know how tall Gandalf was) 15' would be a great height advantage for the demon confronting him. So, thusly, you still preserve the meaning of "great height" without ballooning the balrog up to unreasonable size.
Aside from where Tolkien said that Sauron was taller than the average man, but not gigantic, I don't think the height of Sauron's physical form was ever addressed. I was rather ambivalent to the portrayal of Sauron in the movie. I did not dislike it so much as it just did not fit my mental picture of him.
Oddly enough, I have a pretty clear picture in my head of what Sauron looked like, it's just kinda hard to describe it. It's sort of a large sorcerous figure in very large black, red, and purple robes. He is wearing a thin golden circlet on his head. He's clean shaven and has his hair cut short. (I don't know why, my picture of him always does). The most noticeable thing about him is his terrible burning eyes. He's not wearing massive amounts of armor, but I never really think about him going into battle much. Come to think of it he probably was wearing armor when he fought against the Last Alliance. He probably did not go wading into hand to hand combat with no protection at all.