I've stayed in a Grand Suite on the Fantasy and they are enormous. Lovely big bathroom and a walk-in closet. The sitting area is big enough for the couch to turn into a queen size bed, so huge. And the balcony is huge, too. If you can afford it, it's really nice. If it's just the two of you, an Ocean suite would be plenty large enough. I've been in 2 Ocean Suites (Triumph and Magic) and they are nice and roomy and in fact have a nicer dressing area than the Grand Suites. I had myself and 2 teenagers in all 3 of these suites and we agreed that the Ocean was large enough.
On the other hand, if you have the money and are treating yourself, the Grand Suites are awesome!!!!
Have a great time!