Location, location, location. We did the Millennium in a RS and we had the same issue you had with the distance with the Retreat Lounge and the deck being at the opposite end of the ship. We've done the Apex in a CS, cabin 11113, and loved the location in relation to Luminae, the lounge and the deck as they were all forward on the ship, just an elevator ride away, which was almost right outside our door (never heard elevator noise).