I had the same issue two weeks ago. I was not able to book seats until I was able to check in and, even then, there was no availability other than the seats assigned. But flying Egypt Air was fun. I haven't been in a 737 with armrest ashtrays in a long time. I think it was a 737-300 and it had seen better days a long time ago. But we took off and landed without incident. Also interesting to watch the flight crew enter and exit the flight deck without the precautions we are used to in the US.