The few concerts I've been to were Def Leppard and Bon Jovi this summer at Summerfest. Summerfest always has good bands. It's an 11 day music festival with many different stages in addition to the amphitheater which has the big names that are out touring during that particular summer. http://www.summerfest.com/index.html
I also saw L.A. Guns, Firehouse and Warrant together in Illinois in March. That was a good show. Well worth my 3 hour drive.
I missed Rocklahoma but my brother and sister went. A lot of bands were there like - Ratt, Poison, Lillian Ax, Quiet Riot, Slaughter, White Lion, Vince Neil, Dokken, Winger, Skid Row, Warrant, Firehouse, Enuff Z Nuff, Faster Pussycat, Bullet Boys, Bang Tango, Twisted Sister, Queensryche, Jackyl, Great Whilte, LA Guns, Steelheart, Britny Fox, and Rhino Bucket. I think they are planning one for 2008.