I love my FMIL. Last year they moved to the other side of the country and I miss her terrible.
She has been very involved in our planning. My FI put together a planning blog and I put together a web album of all the pictures/ideas I had to show her. (In my signature are links to all these things.) She is even planning on throwing me a shower which she is sooo excited about.
Basically there are 5 people besides me and FI who are involved in my wedding planning; my mom, my sis, FSIL, FMIL and BF. We plan on having a few togethers with these people to assemble invites, STDs, programs, etc. All have felt very involved, no complaints yet.
Hope that helps, Carla