Canyonlands. This place is enormous, and the diversity of terrain is amazing. After visit Arches the day before and not loving it, I immediately fell in love with this place.

Rocky Mountain. I went just as the first snow was rolling in, and think this is a great place off season. Gets busy with better weather though from what I understand. YMMV.

Redwood. Not as wild, but great hikes in solitude and not crowded.

Olympic. The sheer scale of this place is incredible, and again the diversity is amazing.

I really wanted to go to Lassen Volcanic and North Cascades, which I believe will be similar, but weather and timing were not on my side.