You're right, celticblues. I don't care for opera either. But I do like Denyce Graves.
I have never heard Jewel yodel so I can't say. I will say, though, that there are people who - think - what they're doing is yodeling and it really isn't. Roy Rogers, Elton Britt = Real Yodel. LeAnne Rimes = Sears Yodel. Somebody mentioned Ian Tyson as a yodeling resource, but I have to say, even though I bow at his boots, I do not like his yodeling.
It's like fiddling in a way, there are a lot of fine points that will make you Really Good when you learn them; if you don't learn them, you may be mediocre at best and annoying at worst.