As mentioned elsewhere, I play games too much, so that the software side of things keeps distracting me from diligently finishing the actual cabinet. Mat Mania, Galaga, and Mr. Do are the big culprits. Once I finish, I figure I have to play several games a day to justify the hundreds of dollars I've sunk into the project.
I can beat the nerdiness of just watching the attract screens. When I first got my cabinet home and put the marquee light in, I lay on the couch and fell asleep just looking at the illuminated marquee. I, too, felt like, "Wow, I have a real arcade cabinet!"