In VMware Workstation 10.0.3, things got better, I'm using my 3 monitors under Windows 8.1 64 bit to successfully to run a 64 Windows 7 VM, on all three of my displays, for many dozens of hours per week:
http://TinkerTry.com/enjoy-windows-8-on-lenovo-thinkpad-w520-with-3-external-monitors/
Because the USB 3.0 connected 3rd monitor wakes up after Windows (or after Windows boots), it can be slow for the VM to go back and do triple monitors, when coming out of laptop suspend. I get around this by forcing the VM to have 3 monitors, pictured
I'm playing with VMware Workstation 11 beta (called VMware Workstation Technology Preview 2014) now, and it does claim to have better GPU and video memory support, that may help me, given I'm pushing 7.8 million pixels around, times 2 (Windows 8.1 triple screens, and Windows 7 VM triple fullscreens). We'll see! I really do wish Windows natively could remember all my window positions, even when using a DisplayLink Dock like my Lenovo USB 3.0 Dock:
http://TinkerTry.com/usb3docksuperguide/
Whenever I resume from suspend, it briefly has 2 monitors only, so all windows reshuffled off 3rd monitor. Very annoying, over the years, but I understand Windows 8.1 itself is merely trying to avoid orphaned Windows on some "phantom" screen that isn't currently visible. It seems like a tweak to keep Windows from reshuffling windows so quickly after resume could fix this annoyance.
Wrote a brief tip on getting decent performance on the beta here:
http://TinkerTry.com/how-to-disable-debug-mode-in-vmware-workstation-technology-preview-2014-for-a-serious-speed-boost/