I went down the Mini ITX route.
Coolermaster 130 is a nice small case and fits long graphics card too. If you don't want noise, a GTX 970 is definitely worth considering - or maybe even a cheap GTX 780. I have the same CPU, 4690k, but I went for a cheap motherboard. A CPU is rarely a limiting factor so overclocking is something I could do later - the 4690k was the same price as a 4670 at the time hence my apparently illogical decision.