You really can't fly into/out of Topeka unless you're in the military and qualify to use the air base at Forbes (the nearby air force base). Unfortunately Topeka closed its commercial airport many years ago (I hear they even got federal funds for it....). So you'll most likely fly into Kansas City, which is about 1 1/4 hours away by rental car. Not all rental car companies let you take your rental car into KS. There are shuttle vans that will pick you up...but they all seem to be in pretty decrepit condition, so expect a bone-shattering ride. However, they are not terribly expensive and they do run on time. Topeka says they really want increased tourism, but it's hard to believe they're serious when just getting there is such a hassle.