When you select a Guarantee stateroom know that the cruise line will pick your room location. It essentially guarantees that you will have that type of stateroom, nothing less. The room number could be assigned at any time from booking until the day you board the ship. Keep in mind that these are economically the best option. When booking one you need to know what you are getting in to. I have booked guarantee rooms multiple times without an issue. We aren't picky and so it's fine for us. I booked an Oceanview Guaranatee on the Disney Dream in 2011. Three weeks before sailing we were assigned an accessible room, nearly twice the size of a regular room!
Royal Caribbean's Oasis class of ships offer balconies with a unique view. Rather than looking out to the ocean, you can gaze down upon Central Park or the Boardwalk. These often come with a nicer price tag than an oceanview balcony. Central Park balconies tend to be warmer and quieter as the area is more enclosed. Boardwalk balconies get a little more air flow because the back of the ship is open to the sea. If you choose a Boardwalk balcony toward the back you can watch the Aqua Theater show from your room!
An obstructed view room can offer a great price break for those who don't want an interior but aren't picky about the view. Some obstruction can be as little as 5% of the view, others can be up to 90%. A good travel agent (like me) can get that information for you to help you decide what is right for your trip and expectations!
High Traffic Areas
Sometimes the rooms located above or below public spaces are priced more competitively. I once had a room above a piano bar. We heard the music and singing well in to the night. It was rough because we had our son, at 18 months old, with us. The sound was very hard to manage and we ended up moving half way through the cruise. On the other hand, many people think that being near the stairs and elevator will be a noisy experience, but I have sailed in rooms close to those areas multiple times and actually found them to be some of the quietest rooms onboard!