The Grand and probably Golden Princess have 17 decks. You may wish to find a ship that has only 11 or 12 decks. The promenade deck or one below are usually at deck 4 or 5 and level with the pier/land, so actually you would only be about 8 decks up if on the highest deck which usually houses sports decks, sun decks and disco lounges. The majority of which are accessed by elevators. Dining Rooms, show lounges, casino, shops, pursor's desk etc. are usually mid-ship on the promenade decks or just above. Good luck with yoru ship choice.
Royal Princess will be in the Caribbean out of Ft. Lauderdale after she finished her fall cruises. She is a smaller ship, only 45,000 tons versus the mega monsters that are out now. Hunt for a cabin on Plaza deck, the lowest deck that has passenger cabins. The dining room is also on that deck. The Princess court, with lovely views,music and bar service is only one deck up. the pool is higher, but the pool deck is glassed in, so feelings of insecurity are generally lulled. Just don't go to the Horizon Court, it's on the top deck of the ship. There are only 11 decks on this grand old lady. I just sailed her and remembered what a great ship she is. These itineraries have just been annouonced so you should have no trouble booking her. I believe they will be doing partial Panama Canal cruises.