I have driven between Zion/Bryce and Page three times. This is truly scenic driving.
The slot canyon was quite beautiful but do not expect to exit the canyon that way. Easier to find a game trail out of the canyon, if you plan on leaving through the north end. The north half has no water source so pack a good 6-7 liters. Wasn't the prettiest place to backpack but still worth a go at least once.
Much of this road follows the Vermillion Cliffs, the first of three "steps" of the Grand Staircase. An interesting side trip is to Old Paria, an old movie set that is near the abandoned town of the same name.