Here's the biggest tip for your trip. Don't take 59 all the way down.
At Carthage take the 214 loop around town and get on Hwy 315 it will take you right back down to 59 South but eliminate 15 min from your trip and nice wide roads too. You can see what I'm talking about in the pics below.
No need to take any detours on Saturday in Houston. I drive downtown every day from work and Sat might be a little heavy but definitely not worth a detour. Use Waze if it's SuperBowl weekend or something like that but you should be all good.
