visit Bordeaux region as well as Basque region of Spain

In theory, you could see both in 14 days, especially if you don't aspire to see every nook and cranny of each entire region. But how many days is the cruise you're considering? And where would you fly in/out? You'd have to account for the time traveling to and from your anchor airport(s).

We are looking into Dordogne and/or Bordeaux regions to Spain as well. We will drive for the whole trip. We've been to the Dordogne before, so will spend about 5 days in France, then hope to spend a couple of days driving from France to Spain through the Basque region, spending one night on the way, and then a week seeing, Santiago de Compostela, Bilbao, and the general northwest area. I believe a cruise would limit what you can explore in this area. If anyone has suggestions or ideas about this, I hope you can help. I do believe geovagriffith would get more out of his trip on the road instead of the river.

If we did a river cruise it would likely be 7-8 days. We have rented cars and driven in the UK and drove my own car while working in Germany 35 years ago.

My sense is that the places we want to see are largely accessible by rail.

I looked at the GCT river cruise that goes to Bordeaux and it gives you plenty of time in a lot of the Bordeaux region's highlights. However, it is listed as 15 days, including the travel days, leaving you no time for the Basque country on that trip if your time frame is 14 days. The pre-boat visits to Nantes and Larochelle are very interesting, as are the post-boat visits to Carcassonne and Toulouse. (Everyone likes to bash Carcassonne, but it does have an interesting history and just stay away from the Porte Narbonnaise area.)

If you want to do both Bordeaux and the Basques country, you'd have to do them on your own. Then you'd miss LaRochelle and Nantes--two gems that don't come up on the RS Forum often.

One other issue to consider is weather: the Basque country can be cool and wet until mid-summer, while Carcassonne and Toulouse are scorching in summer. I wouldn't do a river cruise of the Bordeaux region before May or after October, personally.

Since you are an independent traveler, you can take advantage of all those free days listed on the itinerary and head out on your own to have more local experiences (as long as you haven't attracted a following of less experienced travelers wishing to take advantage of your travel expertise).