Select your stateroom wisely.
We live in our staterooms, so we select accordingly.
We only book Edge class on Celebrity, and use our itineraries and staterooms as our personal retreat. The views and the silence broken only by the wind and sea is worth every penny.
We typically only leave our stateroom for shore excursions, spa treatments, lunch and dinners, as well as walking the track, going to the World Class bar (Beyond and Ascent), and Cafe al Baccio.
When we walk the track on sea days, every time looking down to the main pool, it is usually quite crowded (warm climes). Won't do crowds. Won't even utilize the Retreat sundeck, as likewise typically busy on sea days.
As noted, select stateroom wisely and you'll have a memorable sailing, regardless of how busy is the ship.