Feasability of doing two long routes in two days is good if you pick easier to find stuff. Some of the canyons are a bit tricky to navigate your first time up them. Swains descriptions, especially the descents, can be a bit nebulous. Black Velvet canyon is not in the park and has a short approach. Routes are generally in the shade from sometime in the morning on. A good choice for the first day. Most of the good routes in Oak creek canyon are sunny. The walkoff from the upper painted bowl routes is spectacular. Check the moon phase if you think you'll be out late. If its up and 75% or better you won't need a headlamp. GL