Hi there! Our very first cruise was a family one, we were in 5150, my parents in 5152 and my brother's family in 5154. We loved the balconies, tons of space and lots of furniture to sit on. Good location to the elevators and kids club. Nice to see down to the water with nothing in the way. Regular rectangle tub (not the round one). I never felt any engine noise and none of us (11 people in age from 2 to 65) were ever seasick.
But…some people find the extended balconies don't offer much privacy, as people can lean over and see you. There definitely was extra foot traffic gong to and from the kids club, kids running in the halls. We were on the Dream, on the Fantasy I would NOT get 5150, as Pepe's door is attached and has people visiting/knocking it at all hours.
If I was booking on those ships again, I would do the opposite side of the ship and get 5650...