There were several times that the only way we were able to be on the ship were to be on the lower decks (1 or 2) - some times this was a cost issue and sometimes it was joining a group at the last minute. I feel the same way about lower decks that I do about Inside vs. balconies - they are all "eh" to me. My first choice is to be on the ship - regardless of where 🙂 then I start getting picky - I always pick the midship room vs aft or forward, and then start moving up or down decks and in or out. I dislike being forward or aft, as I tend to feel more movement in both those cases (and this seems to apply to be in large or smaller ships, your mileage may vary)
I do feel vibrations the lower we are, but nothing disruptive, and nothing loud. (Again, we do our best not to stay aft or forward though)
I haven't enjoyed staying right below the lido decks on some ships - literally heard deck chairs being dragged around what seems like all night and I swear the halls in the higher floors have a sewer smell to me. My preferred floor tends to be around 5-8 depending on the size of the ship, but again, I haven't seen a room I'll turn down if it means I can go along for the ride! 🙂 Enjoy the trip either way!