Kolob Canyons has a completely different entrance on the highway south of Cedar City. It's higher in altitude than Zion Canyon per se.
It has a nice short drive which can be stunning in Fall color. It's even more rewarding to the backpacker. Second longest sandstone arch in the world is down in there, maybe seven miles in. Don't exactly remember. But I sure do remember how ridiculously cold it could get at night in November. I used my backpack as a pillow to discourage critters. But a particular ringtail was persistent, and kept climbing on my sleeping bag trying to get to the pack. They're a slender raccoon-like creature with a long banded tail and enormous eyes, almost entirely nocturnal, and incredibly cute. But this one pestered me all night. The last thing I needed digging through my Sinar gear was that critter.
Kolob Can is a pretty long drive from Kanab; but well worth it if you are heading that direction anyway. No facilities at all there except the
Ranger Station.
Anywhere in that country a serious sleeping bag, extra food and water, and good footwear and clothing is a MUST, especially in Winter. A stall due to weather or an auto breakdown which might just be an inconvenience in the burbs can turn out downright fatal in stretches of the West where help and accommodations can be far and few between off-season, and cell phone reception unreliable.