I am 75 and had my first experience with mobility issues last year. I agree with the others you should arrange with airlines for wheelchair transport. It is very easy. Egypt can be challenging on your own. I suggest you hire a car and driver/guide for the best and safest experience on the days you want to sightsee on your own. Most major hotels can recommend someone. For longer than a few day trips I have used Audley travel to make custom arrangements. They are flexible and have expert knowledge each country. I was once the solo adventure traveler but now it is time to take it a bit easier especially when traveling beyond the US and Europe. I don’t think age should restrict any of us from seeing the world. Obviously you are enjoying life. Have a wonderful trip!