I agree with what Mike says.
If you can swing a mini-suite or suite you will REALLY love it.
Take the cost of the OS and divide that by 7 days and it's not that much more per day.
We have done the large ships and some of the smaller ones thinking the bigger ships would have larger stateroom but they were exactly the same. The larger ships just have more staterooms and MORE people.
Sure you will enjoy your cruise. When you come back, you will book another one.