It would never be worth almost 3K for me to have the royal suite for just 3 days, especially on a ship with limited suite amenities. We had an opportunity to see the Royal Suite on a recent Marnier cruise and the Royal Suite was very nicely appointed. Given such a short cruise and time out of the cabin, will you really have time to enjoy it?
With that said, it is your money not mine, so I can't make the decision for you. 3K might not be a drop in the bucket for you.
Whatever you decide, have fun.
M