Went to a lot of concerts but only tripped once. Rush, 12/2/1977, Fitchburg Theater. They hadn't made it big yet so it was a pretty small place.
Stage still looked like this with only a single small synth (hidden in the pic).
Elbows on the stage right in front of Lifeson. Was so amazing except for the half hour or so I freaked out thinking the truss over my head was going to fall and kill me.