About 4-5 days, maybe less, maybe more.  

Basic plan is to drive via the Natchez Trace from TN to Jackson MS, hit a couple thrift stores near Jackson, then onto Lumberton, MS (the Salmon/Sterling site), Biloxi (The White House), Venice LA, Port Fourchon, Oak Alley Plantation, Avery Island (Tabasco Sauce) and then Gibsland LA (B&C death site).  Basically, getting to the coast at Biloxi, then hugging the coast as far south as we can going west.

We'll go through NO only to get through it.

Good, bad and the ugly?  Suggestions for other things to see, places to eat, places to stay?  We prefer Hole-In-the-Wall places i.e. no chains.  Seafood and good LA cooking be on the menu!

Anybody?  

If you are heading down to Venice ( waste of time if you ask me), stop in at Adams Catfish House or Salvo's Seafood on Hwy 23 in Belle Chasse.
If you jump over on Hwy 90 before you head down to Fourchon (add Grand Isle since you are close), stop and eat at Spahr's Seafood near Des Allemands.
Avery Island is fun but stop in at Jefferson Island for a tour and lunch.

I live in Lafayette and we have some fine restaurants here.
When are you planning on traveling? South La. can have brutal heat in the summer if you are not used to it.
I would time it with the last weekend in April. Lafayette has Festival International which is an international music fest with artists from all over the world.
Great free festival in downtown Lafayette. Music, dancing, food, and lots of vendors.

Festival International

Oak Alley is really neat. The wife and I typically stay the night there once a year. The mint juleps are good and the breakfast is as well. The house tour is very interesting.

We also stay in Natchez as well. I recommend avoiding Roux 61. Tourists trap with mediocre food. Magnolia grill and The Csmp is where it’s at for food. The cemetery it also a sight to see. Look up Florence Irene Ford grave.

There is also Laurel Valley plantation in Thibodaux. My wife’s uncle is the grounds keeper there. They still have old slave house lined along the road.

I wouldn’t waste the time going to Fourchon unless you going fishing.

Houma is a complete crap hole, but….Cajun Critters is some dang good seafood eating.

We're going to Venice for the location, not the town.  We plan to hit Grand Isle when we get to PF.

Plan is to go before mid-April, but haven't set the date yet.  I despise sweating and the heat when dressed nice.  

Thanks for the help!

I have bad news for you.

Bonnie & Clyde site near Sailes is a bit of a drive from everything you're hitting down South, but come on over! Gibsland Grill & Last Stop Cafe (both in Gibsland) are definitely holes in the wall, if that's what you prefer. You may also try Gap Farms in Arcadia; it's a truck stop/convenience store, but the food ain't bad at all.

Next biggest towns are Minden (west) and Ruston (east); lots of places to stay or eat in either.

Not really:  Sailes/B&C Ambush Site is just about straight north from our 2nd to last stop, which was Avery Island.  Highly recommended BTW!!!  Pretty much a straight shot north towards our way home via I-20/59 and 65.

Bought $185 worth of Tobasco products including gifts for our granddaughter, her parents and my SIL/BIL who took care of our pets while we were gone.  I now have enough Tobasco sauce to last me the rest of my life!  

Whoever said Venice wasn't worth it, was exactly right; very disappointing.  i was hoping to see some water, but we never saw the river except while at the top of one bridge.  

There was a huge NG site being built near Itonton.  We're talking a huge wall completely around it that looks like it was built to World War Z standards.  

Inadvertent double post.

Another vote for Spahr’s in Des Allemands. I have passed by that place untold number of times in my 46 years and just ate there a few weeks ago. Very good food and drinks. I never expected as much. Also, Big Al’s in Houma had some decent seafood(or used to) as well as The Shack, but both are pretty low key, with Big Al having an edge for decor and modernized facilities. I wouldn’t go down past Belle Chasse on LA 23, nor down LA 1, unless you just want to see new mobile homes, old torn up houses, blue tarps and mucky muck.