Granny of the Seas gave you the best description of what you will receive with a suite.
I have cruised four times on Carnival and three times I've booked a suite (Cat 11). I really like the additional room and two of the three suites were an aft, wraparound, balcony. An aft wraparound is wonderful but if your wife is too afraid to enjoy it then a regular Cat 11 is good.
For this special occasion I say go for the suite. I did an AC suite on our anniversary cruise with NCL and it was great. The good part about NCL is that they have "A LOT" more perks if you book the suite. Having said this, Carnival does have a nice cabin for a Cat 11 or Cat 12.
Take care and Happy Anniversary!!!!
Mike