I would not so to St. Catherine to just visit the Monastery - while it is beautifully located, ancient, and wonderful to visit, it's not worth the long drive from Sharm by itself. My mum and me, with many others, climbed Mozes mountain during the night and visited the Monastery in the morning after descending. While climbing the mountain is quite demanding, it is a gorgeous hike. The night skies over the Sinai desert are the brightest and most beautiful I've ever seen. The lightning, far away at the other end of the mountain range, lit up the sky as if in a fairy tale every few seconds. And the sunset at the top is simply divine. The cold (it DOES get really cold at the top, bring a coat) slowly seeping away and the mountains regaining their colours is incredible. Even as an atheist it was not difficult to imagine Mozes there, speaking with God. Do try to find a tour operator driving you there in a coach! We were driven there in a small, cramped minivan, completely unable to sleep.