Well, I suppose this is a pet peeve of mine or something.
In Iowa, the only Democrat willing to run against Republican U.S Senator was Art Small, a 70 year old former state senator.
Nothing against him, but he obviously isn't going to be using this race as a platform for anything else.
Why don't more young up and comers use these races as a platform? The classic I can think of is the then little known Mark Warner in Virginia. He ran against Republican U.S Senator John Warner (to be sure John Warner had lost a little popularity among Republicans at the time for refusing to endorse Oliver North), and used the race to get his name out and learn how to raise money and campaign at a state wide level. 5 Years later he was elected Governor.