Get a powerful workstation like HP Z230 (the core i7 model) and fill it with RAM to max. It takes 32GB. Assuming you let the OS+Installed apps to take 8GB, you have 24GB to give to users. So assume each user takes 3GB for their operations, you can have 8 comfortable users, but that is even on the higher side as each user might require about 2GB depending on what they run... so 12 users hypothetically will be very comfortable.
I am also assuming you will go for the N-Computing's L300 or the M-series... both should work very well. I have worked with the L-series (230 and 300) on WIndows 7 64-bit. I haven't done in WIndows 8 but shouldn't be so different.