Regarding electrical outlets:
I started out with 70 outlets in my game room build-out. Put them closely as it would be helpful once you start to re-arrange the room. Good thing I left the ceiling open and painted black...I have added another 24 since the walls went up. The need for power with neon signs, various appliances like TVs and sound systems, unusual lighted signs in many spaces, and gadgets that seem to use wall-wart power supplies.
I put all the pinball outlets 42 inches above the floor so no cords can be seen, and now I wish I would've added a few more in the bathroom walls. Finding things that can be installed there.
I have 100 amp service running the entire room. Since I have used LEDs exclusively for everything except neons, there's plenty of power for expansion. Plan on using LEDs for everything and you can't go wrong.