For the SNES front, have you tried SNES9x EX
? It's based on SNES9x and is fairly well optimized, and if you have at least a 1.2 GHz CPU you should be relatively OK for most games (except those with special DSP chips like StarFox, Yoshi's Island 2, etc).
Don't expect to get much done on the tablet with emulators though unless you can get a bluetooth controller paired with the emulator. The onscreen controls are all but useless in anything other than turn based RPGs.