I priced on both SNCF and Rail Europe. Total price difference for $500 worth of tickets was $10. Prices were always within a few dollars of each other. I ended up going with Rail Europe due to difficulties with printing and finding the one reservation I booked on SNCF a few weeks ago.
I avoided the OUIGO trains even though they are less expensive.
This is the total price for 2 people - so $250 per person.
I successfully purchased these routes today, with many travel times available for each leg. All travel dates are in Sept and Oct.
Paris - Amboise
Amboise - Bordeaux
Bordeaux - Angouleme - Bordeaux
Toulouse - Antibes
Antibes - Paris.