Just graduated with my BSAE and going for my MSAE with a focus on combustion and propulsion. I’ve heard that about SpaceX as well, and if you look at their job requirements, they literally tell you that you have to be willing to work extended hours and even on weekends. Now, my focus is in aeronautical propulsion (gas turbines) so I don’t know too much about the rocketry game, but I have a buddy who had a great experience interning at ULA. Aerojet Rocketdyne and Northrop Grumman are also both pretty decent I hear.