You know what would be pretty cool for Monks?
Levitating a little above the ground when they're meditating!
You could do this a couple of ways:
1) Just how high they got off the ground would be dependant on what level they were. Example: A 10th level Monk could wind up levitating a foot or two off the ground while a 20th Monk could wind up levitating 5 or 6 feet off the ground or higher.
or
2) When a Monk reaches 20th level, he/she levitates about a foot off the ground while meditating. (I actually prefer this one myself)
It would have no real game affecting utility other than looking really cool.