Congratulations on your upcoming arrival!
I personally would not have him in the delivery room. I had my second almost 2 years ago. At the time, my daughter was 3 1/2 and I too wanted her there because she was so excited for the arrival of her brother and was pretty involved! But at the end, we decided it would probably be too much. Instead, she stayed with my aunt and uncle for the night (he was born at 7pm) and first thing in the morning my girlfriend picked her up and brought her to the hospital. We made a big deal about it and let her hold him right away while she sat with me. She was totally OK with this and was telling us how much fun and all the things she did the night before!
It sounds like you might not want an additional family member in the delivery room, but if you do decide you want your son there I would strongly recommend you have someone there to help. You never know what might come up in the process of giving birth and you probably won't want your spouse to have to care for him when you need him as well.
For us, it was easy getting our daughter ready for his arrival because she was excited about it from the beginning. We let her pick out little things for him, like little onsies, stuffed animal and blankets. She felt like she was part of the planning and preparation as well. We also had her play a big part in naming him.
Good luck with whatever you decide and I hope that all goes well!!!