Originally Posted by UpgradeSolution
Remote desktop through Windows "Remote Desktop Connection" app bundled with Windows is the best bet if you want to do remote logging in as you can just log in with the profile straight from that client. That said, even on my 10Gbps network I still experience some stutter and loss of resolution when using RDC. I personally setup a Window 2012 R2 AD DC on an old box I had that has a i5 4590, 16gb ram, a 750ti and 8x4tb drives in raid5 and it works amazingly well although is way overspec-d for what you want to do. I would say probably go with the 2012 Box and learn about Organizational units and the such as a little extra knowledge never hurt any one and you seem to be in a place where you have the budget to do so, otherwise just go with the RDC client. If you have any questions or need any help with AD DS shoot me a message on here, I am not a full blown enterprise 1000+ server admin but I have been around my fair share of servers and am currently studying for my MCSE.
I do have a little experience with OU's - mostly just deploying printers or simple things (custom desktop backgrounds, limiting access to certain Windows programs, etc.) like that and wow are they useful - they're very useful with only a few computers, but I imagine they would really shine on an enterprise setup.
The one question I have for you would be regarding the specs of a domain controller. You mentioned that your server is a little overkill for running a DC, are you specifically talking about the CPU, RAM, and GPU, or what components are overkill for your build? I had an old Sempron 145, motherboard, and RAM sitting around awhile ago but decided to sell it off a year or so ago - I'd be a little bummed if that would have been adequate for running a DC on.