Received the samples of plexiglass from ridout plastics dot com. We asked for three types: one to demo different colors, one to demo different shades of white/frost/whatever you want to call it, and one to demo the thickness:
While the thickness ones are important, and it helped somewhat to see and touch them (and try to bend them), it's still not clear to me how various thicknesses would stand up when they are 4 feet long (especially in the center when jamming out and slamming buttons in a drunken fury). the samples we got were 4"x6". nonetheless, i think i want to stick with the full 1/4" thick panels. they seem really sturdy. as for colors, i am leaning toward the generic white or frost colors with moderate opacity. i tested some LED lights being under the plexiglass and it actually causes a very cool effect, which would also double being easier because we would not have to mount the LED's in holes drilled in the panels. simply mount them directly under the panel where you want and you get a weird diffused glow.
Going to call the ridout plastics company next week to get a more accurate quote of what it would cost for the full size and if i sent them the specs and had them drill all the holes in advance.