I've read Imzadi at least half a dozen times, and Q-in-Law almost as often.
I've read Destiny twice, as well as most of the NF series. I've also gone back and read some of the TNG relaunch twice, because I read them in a random order the first time.
There are a few other number TNG books that I've read more than once. For some of them it's been almost 20 years since the first time, so I'm sure I'd enjoy them just as much again!