Ryan,
Nice idea, but I agree with the others about mixing the AC with the lower voltage stuff. Many do not know the dangers of AC voltage, and the Arduino is all about experimentation, and making this stuff easy for people just starting out.
Just a suggestion. Build the AC stuff with the opto's on on a 2nd board, then use a small data cable to connect the two. Then the HV section could be put in a external box and protected.
Dale