I personally would never go to Sharm--partly that I'm not diver/snorkler (he's PADI) but I understand it's gotten so horribly touristy and cheap. Some people refer to it as the land of black socks and sandals, referring to the tourist population. I guess I'd equate that with a US waterpark or amusement park (ack--TUBE tops and hiney cracks!!) from yrs of reading forums on subject. I have not been, tho. I would seriously suggest minimizing CAI, going to Luxor--valley of kings is amazing!! Karnak and Luxor temples--amazing! Nile River--amazing!
It seems like you have so much on your plate when you inject the water sport into what most would deem an historical/cultural trip. If your priority is diving, I'd skip Egypt and go elsewhere but that's MY opinion. If you want to see Egypt and Petra, I'd skip diving.
That's just alot of short hops/early flights for standby. MS should be fairly good to nonrev but it's so cheap to buy tkt on the spot, too, if you can't get on. There are SO many flts/day.
I think AMM is better for RTN to JFK at times, but I haven't monitored recently.
Just some food for thought. Keep the questions coming and I'll try to find answers. Hope everyone is getting something out of this thread!