My Princess experience is limited. I don't know the Golden well enough to tell what is a good cabin. But I can get you headed in the right direction.
Bow = front
Aft or Stern = back
Port = left (port has four letters, left has four letters)
Starboard = right (when standing on the ship facing forward)
Low and middle has the least amount of movement.
Princess has different kinds of balconies (I'm referring to kind - not size here). Some balconies are fully covered. Some balconies are half covered and half exposed. Some balconies are fully exposed. By exposed I mean someone from above looking down can see the balcony (the following picture is from the Caribbean Princess) ...
The balconies on the far right are fully exposed. You can see the entire balcony. Moving up one level (the balconies just to the left) are half exposed and half covered. They are considered standard balconies, but are in fact bigger than the mini suit balconies (which are the fully exposed balconies). If the Golden has this kind of a balcony, then that is what I would recommend. Many of the people that post on this board have been on the Golden and will know if the Golden has these half covered/half exposed balconies. Moving up one level (again to the left) are two decks of fully covered balconies. You can not see them in the picture because they are fully covered (but they are there).
As to a guarantee - a guarantee is neither good nor bad. If you are willing to let someone else pick your cabin for you, you get a slight discount and you get a chance for an upgrade. Now, understand, an upgrade can simply be (and most likely will be - if you get one) the same cabin (a balcony cabin) in a better (better in the cruise line's eyes - you may or may not agree) location. You could get upgraded to a mini suite, but that is very unlikely (but it does happen). You will not get anything lower than a balcony, but you don't get to choose which cabin you get. All you are guaranteed is a balcony or better.
Also, check to see if the Golden has any suites without balconies (the Caribbean Princess does). If you really want a balcony, then you may not be happy with an "upgrade" to a suite that does not have a balcony.
