You won't have time to do both. The views are better on South Kaibob but it takes longer to get to the trail head. Bright Angel trail head is closer. Grand View is out of the way. While Bright Angel is in a side canyon it still has some interesting views in that canyon, but not the expansive view of the whole canyon that Kaibob has. I agree Kaibob is a better hike but I don't think as good for limited time (plus hotter and more difficult for a first time Canyon Hiker). Three hours round trip to Ohh Ahh is pretty quick. I would do the bus the evening before to Hermit, and hike early next morning. You will be a little hot and sweaty though after the hike so may wish to reverse that if you don't have time for clean up after the hike but then bring a light in case you don't make it up by dark (and the sunsets won't be as nice from inside the side canyon). The Bright Angel trail is right near the lodge, a long walk or short bus ride from the camp. Probably not worth moving the car from camp. Longer ride to Kaibob trail head, maybe 15-20 minutes but that is 40 minutes round trip when you only have a few hours.