Can bfgminer run on a windows 8 tablet?
No idea on this. Does it run normal Windows software?
Also, should any of nicer android tablets work with the BF units?
At the very least, you'll need USB host support. Be aware that it might not be possible to use AC power or charge in this mode!
Additionally, you may need to compile BFGMiner for Android unless Butterfly Labs makes a public release of their EasyMiner software based on it - I'm not sure if they will or not, but I bet if they know people want it for use with their own devices they probably will.