I doubt the cold in Chicago would bother us - we're Scottish, and rainy, cold weather is pretty much the norm! We travelled previously in the Mid-West in July and survived, but that was more of a dry heat. Definitely seems that April, starting in New Orleans and ending in Chicago is the way to do it.

Will definitely look into the Bourbon Trail - we like our whisky and have enjoyed distillery tours at home, so sounds like a Bourbon distillery would be right up our alley.

The parkway tips are great also - scenic drives always appreciated.

Thanks very much, everyone, for your full and informative responses!

I'm not sure I'd go all the way to the Smokies for just one day - it's the most out-of-the-way destination, and will add about 8-9 hours of driving to your trip for just one full day in the park. If it were my trip (which it isn't :) ) I'd think about just an overnight in Louisville and adding that full day to GSMP.