Not another - Which Distro? - Thread

Well, sorry to disappoint you all, but this is another: Which Distro? thread. However, I hope to achieve something a little different from most other threads of this nature. My goal here is not for a shouting contest of which distro is best for noobs, or which is the most powerful/lightweight. All I want to do is to pick the brains of those who have much more experience in the Linux world than I.

First let me explain a little about myself, before I direct you to my main questions. I have been using PC's for about 15 years (I'm only 22), until two years ago when I bought a MacBook Pro. I would classify myself as a nerd, geek, what have you and as such am rather passionate about this field. (If I wasn't why would I be reading The Verge) I have no problem breaking things and figuring out how to fix them, in fact that is part of the reason for why I am here today. I guess you could call me a power user, as I spend most of my time fixing systems for other people. (OK, that sounded rather arrogant)

Now to the crux of the problem at hand: At work we recently started selling a software/system package that runs on CentOS 5.4, a color-corrector for post-production, and where we are usually the customers first point of contact when things go wrong. I am finding that I need to learn more about Linux in general so I will be able to help customers when the time comes. Some of you may be asking, why not just load up CentOS and use that. Well, I find I learn best by submerging myself in the OS and therefore I am looking for something I can run as my default OS and something I will use everyday, something that from my limited experience CentOS is not the best for.

Question 1: What distro would you recommend? and Why?

I am looking for something that is based around the Red Hat environment, as I want to stay a little attached to CentOS for work.

Question 2: What desktop do you recommend? and Why?

I really want something that is sleek and elegant, as it is going to be used as my daily driver. Ideally something that is Themeable, if you have a favorite theme then let me know.

I have tried Fedora 17 recently and found Gnome rather... umm different, but in a good way. I am willing to consider a different kind of desktop to the typical paradigm of Windows and Mac, but not being able to easily minimize windows was a bit distracting.

As I said above my main point here is not for a shouting contest, (OMG, DistroX is the best, most awesome ever!) but a discussion over the pros/cons of the various distros available. Apart from that, let me have it!

(People always say I talk to much, I guess I post to much too.)