Whatever you decide, I'd strongly encourage a wider access. Having to squeeze in now will get old later. Also, as much as you don't want to believe it, you will probably get bigger and it could become very difficult for you to squeeze through. There are also visitors to consider and it could embarass someone who is too big to fit comfortably through the opening.
Gates are good but I really like a lift out section. It only needs to be as wide as the right of way for both tracks. It keeps the weight and bulk down and should be pretty easy to handle. This approach also allows you to get fancy and substitute a staging yard module for the bridge if you want.
I also wanted to comment on the train room pictures. Isn't it amazing how fast a flat surface becomes a storage shelf? 
Nice benchwork, by the way.
