For me...I enjoy greek due to a combination of things.
Mainly, it's the idea of taking part in an activity that most providers want no part of...so it's kind of an added bonus when the opportunity presents itself. I won't pay extra for it, so it isn't something that I feel like I have GOT to have, but on occasion there are ladies that offer it during play time and I will always jump at those chances.
Visually, I like watching my cock slide into her ass. It fucking turns me on...
I have also noticed on many occasions...when you fuck her pussy, she will have her normal moans and other sounds of pleasure. However...you start tapping that ass...and she will let loose with a whole different set of audibles. That again, is a turn on.
The initial tightness as the head slips through her hole and the feel of her squeezing the base of my shaft as I push it all the way to my balls...again...is a major turn on.
I don't really look for it that much anymore as my UTR loves it in the ass and she doesn't upsell me, so if I get a hankering to pound some booty hole...I just go see her.