This is a pretty easy question to answer analytically. I wonder why Radisson just doesn't do some discrete choice analysis. It's a proven method used all the time in extremely complex industries, like pharma and financial services.
They could use the following test samples:

1. People who have never sailed on Radisson
2. First time cruisers who have booked but not yet sailed
3. Cruisers who have completed 1 cruise
4. Cruisers with varying levels of nights on Radisson.

The brands to be compared would be Radisson, Oceania, Silversea, Celebrity, and Crystal. They should be able to determine what the relative utilities are for different levels of features (truly all-inclusive vs. partially inclusive vs. non-inclusive, etc.).

It's then easy to calculate impact on likelihood of moving customers through the acquisition/retention funnel and of course the optimized fare levels. Having worked with a number of clients in the travel & leisure industry over the years, I've found that the m.o. for executives is to make decisions based on their gut experience (this is also true of executives in retailing except for Neiman Marcus, Wal-Mart, and Best Buy from what I have seen) rather than using quantitative best practices.