Peoria, Illinois is a great place for hard rock/metal bands. Not too far from Chicago or Springfield if you want to move around a little.
It's at least 350 miles in any direction to the next sizeable city from Boise.
Scratch that... next 'city'. I consider everything closer to be towns.
Theres alot of that problem out west. (With the exception of the southern california, phoenix Az area).
Anyone living east of say, Chicago, has it easy.
Thankfully boise is steadily getting better as a music town.