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Consensuses is RCCL or NCL.
RCCL has better outside lido deck space/pools, NCL is somewhat tight on the lido deck.
Rccl Flowrider, ice rink.
NCL better water slides. Although check height requirements.
NCL better up-charge dinning.
NCL better late night crowds and party.
RCCL has water included in the beverage plans. NCL does not.
Rccl, better adult spaces.
It's a tough call. If you are young, or a group, book NCL.
If a family book Rccl. JMO.
Rccl has calmer, and more amiable folk on the cruise line boards.
NCL folks are a bit ... brutal and abrasive. Although they do have great heart and intentions.
Although misguided at times.
New NCL ships have dining on the promenade deck. It is also open for relaxing/strolling.
Some Rccl vessels lack a promenade outside deck.
Having said my rant.
You have a 6 y/o.
Many praise NCL's kids clubs.
They are closed for lunch and dinner for and hour, unless you pay for prior arrangements.
Not sure of Rccl's kids club hours.
Kid Clubs;
My kids liked all kids clubs about the same. Not much.
DCL least, Rccl medium, NCL best, ;
If I / they had to rate them. But my kids are weird, introverts like me, so...
DCL is always a free for all. Rccl a bit tighter. Ironically NCL has really tightened it up lately. And impressed many families.
Although a 6 y/o will not be able to slide on all those visually imposing slides On NCL.
My thoughts for the night.