Be careful that you are comparing services and not cruise experience. I have only cruised HAL so far (so admittedly not an experienced cruiser) but I read this board everyday. Carnival and HAL will give two very different experiences. I want a quiet relaxing cruise where I can sit in the sun, see the ocean pass by, and read. No excessive noise or poolside entertainment like belly flops & hairy leg competitions (some days I could win that one). I love cruising with the older generation (I am 47!!). Couples enjoying the music, dancing (swing, foxtrot etc), afternoon tea, no excessive drinking. Staff giving extra care to the more senior cruisers. The ship is still and quiet late at night. I would not bring my teenagers on HAL.
I gather from my readings that Carnival is an active, party, alcohol rich, and youthful atmosphere with activities late into the night. I believe that Princess and Royal Caribbean would be somewhere in between but more active and family oriented. My 2008 cruise will be RCL or Princess with my mother and sister (50th b-day). My sister was bored on HAL and loved RCL. Her boyfriend won the hairy back competition!!
I need to hear comparisons about cuisine, staff and entertainment. Please be clear so I can understand what you are rating.
This board is so informative but we have to remember that not everyone is looking for the same experience. Not even sisters.
Finally getting back on a Dam ship, Nieuw Amsterdam Nov'11 (My Mom's 80'th B'day cruise)
Navigator of the Seas 2010
Serenade of the Seas 2009, 2011