If you're going for the under-$800 crowd, I don't think I'd change a single thing. The very best CPU and GPU available for such a build, a nicely-featured motherboard, plenty of RAM, a SOLD power supply (Seasonic is great), plenty of storage in one of the better-rated HDDs around, and a case. I don't pass judgment on others' choice in cases, though I don't think I'd buy that particular one myself. Still, Antec makes solid cases. The only thing that's missing is an SSD, and that'd totally blow your budget. Maybe down the road you'd want one, but otherwise, wow. Good choices all around.
Welcome to TR, btw.
I do not understand what I do. For what I want to do, I do not do. But what I hate, I do.
Looks great. If you're planning to add a second graphics card, though, you may want to bump the power supply up to the 600-650W range. And add a nice tower heatsink for the CPU (I recommend the Hyper 212+). The stock cooler will do you for a spell, but it's not quiet or terribly good.