I have a good friend who had the gastric bypass as did 2 of her friends and there is someone in my office who also had it done.
Each of them gets filled up very fast. All but one have gone on a cruise and their only complaint was that they could only eat a small amount of the delicious food.
Drinking is a no no and can affect your liver.
Each one had a different post-op experience and each one a different eating experience but all of them lost lost a tremendous amount of weight and are living a healthier life, avoiding the pitfalls of high blood pressure, diabetes and heart disease.
I would wait at least 6 months after your surgery before considering a cruise (that's from my friend). Each of the four people I know had problems the first 3 or so months after surgery.
Fast forward to now...
One person can eat anything he wants without any side effects. Two can eat almost anything and one has to watch what she eats or else she gets sick. Some have to avoid pasta, some sugar, it just depends.
I would find a Gastric Bypass board and get the info from these people first hand. I am by no means an expert, just a friend of some people who have had it done.
If you decide to do it, it will drastically change your life for the better.