Depends on what you want and how much you want to spend.
Both types of cabins will have balconies. The Upper deck balconies will look out on the water and have cabins above and below so would tend to be quieter. The Veranda deck would look out onto the Lido deck but should also have an enjoyable view of the water. The Veranda deck is just below the spa so if there is noise it shouldn’t be at night.
Either way with a balcony you are not going to feel closed in as an inside cabin might. There is probably not enough difference in motion between the cabins to make that a deciding factor. The Veranda deck will probably have a different feel since you are at a level with open decks so you’ll feel more part of the action than lower on the Upper deck. However, the upper deck is about half way between everywhere you need to be.
From the pictures on Carnival’s web site the Cat 11 suites on the Veranda deck looks just like the standard balcony cabins on the new Carnival ships. The Cat 12 Penthouse suites would be bigger.
Hope this gives you more information to help you with your decision.
2012 Carnival Destiny
2011 Carnival Splendor
2011 Carnival Pride
2010 Carnival Legend (w/ Hurricane Paula)
2010 Carnival Imagination
2009 Carnival Valor
2008 Carnival Freedom
2008 Carnival Facination
2007 Carnival Triumph
2006 Carnival Miracle
2005 Carnival Victory
2002 Carnival Imagination