Anyone know of a good GUI for RetroArch (should be possible, since the main executable is commandline-based) that allows more easily selecting a console/core (with individual configs for each) and selecting a ROM without manually browsing and selecting the core, ROM file and config every time you want to change like in phoenix?
Hyperspin 
Currently, Phoenix is the only GUI I know of. In linux, I use desktop launchers (i.e., scripts) that load all of that stuff on an individual game basis. You could do a similar thing in Windows with bat files.
EDIT: oh yeah, that’s true that you can use Hyperspin or other frontends like XBMC with Advanced Launcher and setup each core/config combo as its own system, then you just have to search for the individual ROM and it will load it up with that core/config.
I can say Retroarch with XBMC´s Advanced Launcher works pretty well, since i found it i use this XBMC thing for everything
Cheers!!
XBMC is really nice! my setup launches all my PC games and hyperspin. when i exit out of hyperspin, i’m back in XBMC. you can also make XBMC work with a wireless controller without the use of joytokey\xpadder!