Depends on which ship you're talking about. On both Mariner and Voyager all of the staterooms from H thru D are the same size ( 356 sqft on Voyager and 301 on Mariner). On Voyager the lifeboats stick out a bit and there is some view restriction on the lower decks; not the case on Mariner. If you haven't cruised RSSC before I'd choose something amidships in the Cat E and F arena. If you're talking about Navigator, which has some window staterooms, I'd take something on deck 6 just forward of the atrium starboard side. The Horizon suites are no larger than the others; you just have a larger deck. Some like them and some don't. Not worth the extra money in my humble opinion. You will have to pay a single supplement for two single rooms. Bunk together if you can.