We've sailed on Orchestra twice in an Aurea suite. Both times we had a fabulous trip, excellent service and food. No issue with menu size difference or slow embarkation. The ships without YC are, as previously stated the older ships, less glitzy but more intimate. Both of our cruises were port intensive so we weren't looking for facilities and events on board during the day. We thought the suite spacious.
A lot will depend on your itinerary and time of sailing. We always sail off peak so enjoy a quieter time. If you're travelling in the school holidays, I'm not sure it would be as quiet and relaxing.
We've sailed on Meraviglia and Seaside in YC and I'm not sure if I'd be as happy not in YC on those larger ships.