We had a houseful again until 3 weeks ago...my MIL lived with us for 3 mos. after she and my FIL got sick, until we could move them into assisted living.
During that time, my 3rd son, then 26, moved back home in order to pay off bills and get his house in order. Then, the week after my MIL moved out, my oldest son moved in, having transferred back to the area from Minn. Seven months later, after he married his fiance, she and their dog moved in.
They moved out 10 months after that. My third son just got married last week.
So it's quiet again. We made the mistake of not charging him rent...made it too comfortable...it took him 2 years to find a job that was full time (he'd been working 2 part time jobs). Once he got the full time job, he bought his girl a ring, and they decided to get married in 11 weeks!
Make sure that they contribute in some way, either by giving you rent, or buying groceries. Our food and utility bills have gone way down since my son moved out...esp. the electric bill, now that his computer and music mixer aren't sucking juice.
My DH loves the empty nest, but I admit I miss the kids...added to that, my youngest, our only daughter, graduated from college and decided to stay in Wis. So I really am going through a rerun of empty nest anxiety. Why don't dads feel the same way?
Good luck with the change...make sure you communicate honestly with them when you feel anxious about any noise/mess/costs. Otherwise, you'll bottle it up inside, and we all know that's not healthy!