With airlines, you can concentrate in one program and, if you're careful, the rare times you need to fly on a different airline, it'll be in the same alliance and you'll receive enough elite benefits to make it tolerable.

But I think a good case could be made for maintaining high status in multiple hotel programs. It tends to be easier, especially if you have many short stays.

Specifically, I think Priority Club Platinum could be a great addition to Hilton Diamond, especially if you ever find yourself traveling to obscure smaller towns. You'll then often have your choice between a Hampton and a Holiday Inn Express - and one of them is likely to be good enough.

It's relatively easy to achieve Platinum in Priority Club using the info in the forum here. They are generous with point bonuses and (almost) all points count toward status. It's reasonable to expect Platinum in 7-10 stays if the promotions line up right. Then you have a legitimate backup plan if Hilton lets you down.