The biggest benefit is actually concierge lounge access, which is good in the US, and excellent in Europe and Asia. If that doesn't matter to you, then based on what you've written, I don't see any reason to go out of your way for 50 nights.

You also get more points per stay, an occasional room upgrade, and a few other minor benefits.

For me, breakfast/appetizers/drinks in the lounge are easily worth a few hundred dollars if I were just 3 nights short. But only if you plan on using the benefit.