Always choose a cabin with other passenger cabins above and below. That's my number one piece of cruise advice, whatever line you sail.

Don't discount Carnival. The primary difference between Carnival and Royal is the size and amenities on the newer ships. When comparing Monarch/Majesty to Carnival's Fantasy class, there's not much difference.

Consider the 3 or 4 day on Carnival Imagination out of Miami or Carnival Sensation out of Port Canaveral (which actually has regular balcony cabins). Carnival Ecstacy is also offering new (for Carnival) 4 and 5 day itineraries out of Port Canaveral. All of these are Fantasy class vessels and will be comparable to Majesty and Monarch in terms of size and amenities.

I also always recommend the 4 and 5 day sailings on Carnival Inspiration out of Tampa, as even though it's an older ship it's one of the best-run in Carnival's fleet. We've sailed her three times.