Ohhhh, I LOVED Mad Monster Party. I'll go as far as to say it was my favorite of all the Rankin/Bass specials, more so than Snow Miser and Heat Miser, or Hermey the wannabe dentist, or any of those Christmas specials. I just adored monsters that weren't too frightening, and Francesca was one cool chick.
PopBunker has a great post reminiscing about the special. Were you a fan? Did you like the other Rankin/Bass offerings, or did they creep you out?