You can't go wrong with either one.
I never stayed at the Royal, but it definitely is nice and more upscale than the GPR.
Seeing as I never can get enough of Playa, I'd probably stay the extra night at the GPR.
If you don't have kids, the Royal is probably where you want to be though.
Again, you'll enjoy either place....perfect location, great service, great people. Did I mention perfect location!!