As an ex-KC'er, I have a few ideas for you:
If you haven't already, check out
www.kansascity.com. It provides local news and general info about the city.

The Plaza is a good first stop...south of Downtown about 30 blocks. Good walking, great restaurants. There's tons of *yawn* shopping, but there is a Sharper Image store for a fun diversion. The architecture on the Plaza is reminiscent of Seville, Spain. And you can catch a movie there, too.

The biggest entertainment district is Westport -- south of downtown 20 blocks. There are some decent bars, good live bands, tho on weekends it's overrun by "21 year-old" wannabes. The Grand Emporium, near Westport, usually has the best live acts.

Remember, you will be in Missouri most of the time. In fact, if you drive I-80 E / I-29 S and stay downtown or at Crown Center (with the convention at Bartle) you will not be in Kansas during your visit to KC. That's a good thing. If you do take I-70 -- sorry about the 846 miles of the state that you have to drive thru. OK, I got the Kansas slam out of me. Actually, I think the best nearby off-roading is at an ORV site about 100 miles West of KC (Tuttle Creek?). The HXOC has been there in Winter and Summer, I believe.

For other fun drives off the blacktop, check out some of the roads that parallel the Missouri River to the Northwest of the the city. MO 45 is a two-lane highway with gravel/dirt spurs that lead to the river or climb a couple hundred feet into the bluffs. About 35 miles NW of downtown (off of MO 45) is Weston Bend State Park. There's good hiking along the Missouri River or atop the bluffs that rise above it. Five miles further is the town of Weston, with a few restaurants, several wineries and the home of cheap vodka -- the McCormick distillery.

Speaking of being driven to drinking...the Royals are in town playing Detroit (which KC should win) and San Diego that week. Kauffman Stadium is in the inner Missouri 'burbs at I-70 and I-435. The stadium is in remarkable condition that belies its 30-year age.

Two other things -- if you like (or even sort of like) barbecue, head to the 'hood at 14th and Brooklyn and get a sandwich and fries from Arthur Bryant's. Best BBQ in the world and an historical atmosphere that adds flavor to the sauce. Near there (18th and Vine) is the Negro Baseball League Hall of Fame and the Jazz Museum. Both are great tributes to a forgotten time and definitely worth a look.

Decent places to go to get out of the humidity (and at least people watch) are at one of the several Casino riverboats. There's even an Arthur Bryant's on one of the "boats". Note the quotes -- all of the boats are actually floating in tubs of water within 100 yards of the river. (A legal wiggle to get gambling passed about 10 years ago) They aren't bad for gambling tho, with Vegas rules on Blackjack and high limits on bets.

That's about all I have to say about that.