There are also public hot springs around northern NM...check out stagecoach hot springs near Taos, and the several near Jemez (McCauley, San Antonio).
I honestly think PeFo is too far to really be worth it. I was just there this weekend in fact, and my wife and I both agreed, its got some neat features and great scientific resources, and the somewhat monotonous large-scale scenery hides some colorful and interesting little spots. But just on the merits as a visitor attraction, its not really massive-detour material. Carlsbad Caverns on the other hand, is simply an astounding natural feature. Try to get on one of the ranger-guided tours to other caves or other parts of the main cave, they're excellent.
I might even bag the trip to Canyon de Chelly, save that for when you come back to see PeFo...replace it with Chaco Canyon or Mesa Verde and/or Aztec Ruins. Aztec is under-visited compared to the others, but its the only one that has a full replica of a village interior, showing what a great kiva was like while in use ~800 years ago. Its quite dramatic and really puts a new perspective on things (we tend to envision people living in the ruins as they are today, without reconstructing the centuries of deterioration).
Anyway, You can have plenty to do in six days with what you're talking about now (never minding the huge side-trip to Ouray...I love Ouray but with everything else that's still on the table, I'd probably recommend just tooling around northern NM)