Quite a few acts have impressed me that I was not expecting. Here are a couple.
Back in the early 70s, I went to see Humble Pie. The opening act could not make it and there was a different opening band I never heard of before called Gentle Giant. Well, I was amazed by them and have been a fan ever since.
In the early 80s, I went to a Loverboy concert and the opening band was Huey Lewis & The News. They were fantastic, super tight, and full of energy.
Ha! In the mid-80's, I saw Huey Lewis and the News as the headliner. Opening act was some virtually then-unheard of guy called Stevie Ray Vaughn and Double Trouble. Holy $hit! Stevie in his pre-sobriety days DIDN'T SUCK!
Stayed for the Huey show, but fell asleep after SRV.
dcr

Took my nieces when the were 12 and 13 but I enjoyed them also. surprisingly good shows.