Ann,
I'm 51 and my DW is 45. There are all mixed ages on Carnival. YES!, they are known as the "FUN SHIPS" don't you want to have fun? If you prefer a cruise were everyone is over 70, which happened to us on NCL to Canada, then go for it.
All children on Carnival ships are put in either the Circle C for youngins or the teenage area for, well, teenagers. We have yet to have a bad time on ANY Carnival ship. I tell people, don't listen to what you have heard, try it. We are going on the new" DREAM "ship on Nov 13, 2 weeks , for a 2 day cruise to nowhere, then in May we are going on the "Miracle" to the Bahamas. This past April, we did the Miracle to Bermuda.
Go to Carnival.com, look for John Heald's blog. I read it on a daily basis, it's filled with alot of the happenings.
OK, we have never sailed on RCI, we have thought about it. The price is a little higher on RCI. And getting to Bayonne adds more $$ we would rather have on the ship.
Check out the Hilton hotels in NY city, or the "W" hotel, they are very nice. I recommend the Hilton on 6th near Radio City Music hall.