You are going to see the headliner of course, but did you ever miss the opening act because you had no idea who they were,didn't care, or wanted to finish a couple more beer in the parking lot?
I will always regret, staying in the parking lot to have a couple more beers while a relatively unknown band did their show, opening up for Iron Maiden. That band? Guns and Roses, appetite for destruction tour. Awesome album, but ignorance cost me a chance of a lifelong memory.
Recently I saw KISS for the first time and Buck Cherry was opening for them. My best lifelong friend insisted there was no point in seeing them because he had no idea who they were. I liked and new some of there music and finally convinced him to go in after about 3-4 songs had played and after the show he said "good call on that, they were really good."
I will never miss an opening act again. You see some dogs, but can witness some gems.