I like the aft-facing catagory BB balcony cabins; or any balcony cabin on Caribe Deck, because the balconies are larger. Or if you like to spend a lot of time around the main pools, the balcony cabins on Lido Deck are very conveniently located--as are the inside cabins on Lido Deck.
I don't think you'll find Emerald Princess to be too big. I like the smaller ships, but the large ships have advantages too. The only way to find out which is best for you is to try both.