I get why people have backup programs, but I stick with Marriott even after hitting platinum. They are almost everywhere in US which is where I primarily travel for business and then concentrate on where they have hotels for vacations. This does mean occasionally I have places where I would like to go, but redemption precludes that.

Another big reason is that when they changed the platinum bonus from 30% to 50% a while back, it is a very good incentive. And I redeem how the OP redeems, week long vacations in nice places. If I had a secondary program, I just think it would take too long to get that many points. All comes down to personal preference I guess.

Cheers.