Road trip from Kansas City to Boise

The fastest route from Kansas City (Missouri) would be I-70 to Denver, I-25 north to Cheyenne, I-80 west to Salt Lake City, I-15 north to just north of Ogden, then I-84 to Boise.  If you're looking for educational stops, you could follow the Oregon Trail route by taking I-35 north to Omaha, then I-80 westbound, stopping off at Fort Kearny State Recreation Area, then when you get to Ogallala switch to US 26, stopping off at Courthouse & Jail Rock, Chimney Rock National Historic Site, and then overnighting in Scottsbluff and checking out Scotts Bluff National Monument.  Continuing on US 26 into Wyoming, you could stop off at Fort Laramie National Historical Site and the preserved Oregon Trail wagon ruts at Guernsey, then overnight in Casper (Wyoming) and check out Fort Casper Museum.  The next day, take Wyoming Route 220 to Independence Rock State Historic Site, which is a very cool spot where you can actually climb the rock, which rises about 200 feet above the surrounding flatland.  Then, continue on Wyoming 220 to US 287 to I-80 and head on I-80 into Salt Lake City and check out the Mormon Church sites such as the The Tabernacle on Temple Square, Temple Square, The Beehive House and This Is The Place Heritage Park.  Spend the night in Salt Lake and eat at one of the many great restaurants, then head north on I-15 to I-84.  Another good Oregon Trail site between Salt Lake and Boise is Shoshone Falls Park just outside Twin Falls.  If you played the Oregon Trail computer game as a kid you might remember all of these sites...just make sure to pack a dutch oven and plenty of bacon, saleratus and laudanum, and don't accidentally shoot yourself hunting buffalo or die of dysentery :-P