So I'm looking to do my first PC build, which I plan to use both for work and for a little bit of gaming.

Professionally, I'm a statistical geneticist, and do a fair amount of programming and analysis of medium sized datasets (i.e. stuff where putting it on a cluster is probably a bit overkill/more trouble than it's worth, but which will still take some amount of time to run on a regular PC) and I play games like Kerbal Space Program and Cities: Skylines and just want them to look nice and run smoothly at reasonably high settings on a big, high resolution screen (currently I play both of these on a 2012 Macbook Pro, which is fine, but not ideal).

The build below is probably at the upper end of my budget (i.e. I was looking to go a bit cheaper, but then I started picking parts and this is where I landed; you know how it goes), so any feedback on where I might cut costs would be appreciated. I'm particularly clueless about my video card choice, as it seems there's an opportunity to swing a few hundred dollars there, and not really sure what I need. What kind of difference would I see if I shaved $100 off the video card, and if I did, what should I go with?

Buying parts in the USA and yes, have read the sidebar.