I've based quite a few trips Europe to US around concerts by my favourite singer -last one was a multistop LON BWI PHX YVR LON so I don't see anything wrong with your trip
. It's a great excuse to visit new places and have some fun (and if you can use miles for it or make it a mileage run all the better
)
I've always found the fan community the best place to get tickets-and I've met some really nice people that way as well as getting better value for tickets than an agency.
Really enjoyed your report and loved your photos -Thanks for a fun and informative trip report.