Suggestions please, how to travel from Lyon to Saintes or Rocheford, (either is closest rail station to destination Marennes). would it be less hassle TGV via Paris, or, how many changes cross country SNCF Montlucon/Limoges/ Saintes. With two large suitcases!
The French railways aren't good at cross-country journeys avoiding Paris due to the level of centralisation. There is one daily through train from Lyon to Bordeaux via Limoges, which leaves Lyon Perrache at 1229 and Lyon Part-Dieu at 1240, and gets to Bordeaux at 2036. There's then a train from Bordeaux to Saintes at 2100, which arrives at 2225. From my timetable there doesn't seem to be an easy way to do that route using consecutive trains at any other time of day. Going via Paris normally would involve crossing from Gare de Lyon to Gare Montparnasse, which is a bit of a trek by Metro with two large suitcases. One alternate possibility is to use the trains that run from Lyon and Bordeaux to Lille via Marne-la-Vallee on the outskirts of Paris, which avoids having to cross central Paris. The options are: Lyon Part-Dieu 0559 - Marne-la-Vallee 0749 then Marne la Vallee 0833 - Bordeaux 1243 then take the 1252 or 1444 to Saintes. Lyon 0830 - Marne-la-Vallee 1022 then a tightish connection to the 1034 arriving at Bordeaux 1453. The next train to Saintes isn't until 1707 though. Lyon 1130 - Marne-la-Vallee 1322 then Marne-la-Vallee 1434 arriving Bordeaux 1843 for the 1852 or Fri/Sun-only 1953.
The German Rail site gives several routes throughout the day, some with multiple connections. These have only one connection, but both take two hours longer than routes using TGVs: Lyon Part Dieu-Toulouse-Saintes, departing at 09:10 and arriving at 18:31. Lyon Part Dieu-Bordeaux-Saintes, departing at 12:40 and arriving at 22:27. The SNCF site gives these routes which avoid having to change stations in Paris: Lyon Part Dieu-Massy-Angouleme-Saintes, departing at 06:30 and arriving at 13:27. Lyon Part Dieu-Marne la Vallee-Angouleme-Saintes, departing at 08:30 and arriving at 15:01. Lyon Part Dieu-Marne la Vallee-Angouleme-Saintes, departing at 11:30 and arriving at 18:42. Lyon Part Dieu-Massy-Angouleme-Saintes, departing at 14:30 and arriving at 21:14. Lyon Part Dieu-Massy-Angouleme-Saintes, departing at 16:30 and arriving at 23:00. For any of these routes the timetables might vary a bit on weekends. Whichever route you choose, I encourage you to pack lighter. You can do it and you won't regret it.