Hey Craig - I figured it must be sabatical time...it's been about 6 years since you went to the NATCOA thing in Nebraska.
You already know Colorado, so I won't bother with suggestions there but if you are wandering CO let me know (we are very close to Boulder but I'm sure you'll have a lot lined up for that part of your trip.) It'd be fun to catch up over a brown ale or something....
A place in Arkansas we've liked, and especially wished we had a boat with us when we've stayed there is a Corps of Engineer's site called Spadra which is near Clarksville, Arkansas. We were visiting a friend who was going to school at College of the Ozarks and have stayed there a few times....anyway, it is on the Arkansas River where it is relatively backed up with dams and locks, but it would be a lot of fun to get on a boat around there with the flooded lowlands along the river. Right off the interstate so if you happen to be along there....not a "destination" but if you ended up nearby.....
In LA, you should get out to the bayou (Athcafalaya) east of Lafayette. There are boat ramps off of I-10 at the Butte La Rose exit to get into Henderson Lake and there is a small corps of engineers CG west of the town of Butte La Rose on the canal. And if you want to some good eatin', try the "from the swamp" platter at Pat's in Henderson. Sleepy had some write-up on Pat's in his long TR....but it's well worth going to. In that neck of the woods, you can also go to Avery Island where Tobasco is made and take the tour and drive around the gardens.......and buy shrimp from the boats in the right season at Delcambre. That was a fun day trip for us when we were there.