I just wanted to share a little advice from my own experiences and from what I've been reading on these forums. It is my belief that there is some bad advice going around, and I just want to caution others. You will often hear "Just address the invitations to the people invited, and they will get the hint." WRONG!! There are so many people out there that do not know proper wedding etiquette, and lets face it...most of us didn't either until we started planning our own wedding.
Anyways, if you want to ensure that only the people you intend to invite RSVP, then the BEST thing you can do is put on the RSVP card "___/___ seats have been reserved," and fill in the amount on the right. This way, no one can assume they get a plus one (or in my case plus one, plus two, plus three), and it helps iterate exactly who the invitation is intended for. I addressed my invitations to the specific people I wanted to invite, but I forgot to put __/__ seats have been reserved....well, I have been receiving RSVPs left to right filled with extra guests. Please, learn from my mistakes!
Also, save yourself and your guests the "guessing game" and just put "Adult Only Affair" on your invitation if you do not want children there. It is NOT rude!! I promise you, as a parent, I much prefer the clarity and have never been offended by receiving an invitation that said that. Just do it!
Also just for fun, here is a recent story to help share my experiences. There was a wedding invitation in our mail for FH's cousin's wedding, and it was only addressed to him. So I had to contact his mom and ask if me and our kids were included in the invitation. She said of course, and had no clue why I would of thought otherwise. See, again....most people don't know all of the "wedding rules" so please don't assume they do. Anyways, just wanted to share my 2 cents and experiences in hopes it might help others. Happy wedding planning all of you brides (and grooms) to be!!! 
