Corsica and Sardinia

What does "RS experience" mean? A tour?

A Rick Steves experience…some guided/ some on-your-own, behind the scenes, adventurous, nice but not luxurious, etc.

There are several posts on the forum about Sardinia and Corsica. If you look at the top of this page you'll see a "Search" bar. Type in Sardinia, select "Travel Forum"and then select the amount of time (1 year. or 2 years, or 6 mos.) to reduce the responses you will see.
In general, Sardinia is large, and so is Corsica, and 6-10 days is a very rushed visit if you go to both. Some would say that 6-10 days is a rushed vitas for Sardinia (which is larger than the Big Island of HI). I have found a lot of useful info on this blog. Maybe she has some recs for guides:
https://strictlysardinia.com/blog/

With only 10 days you can only visit so much. Corsica is as large as the Big Island of Hawaii. Sardinia is more than double that size.
You could rent a car and visit the south of Corsica and the north of Sardinia (Gallura area), but splitting your stay. There is a car ferry that goes back and forth between Bonifacio (Corsica) and Santa Teresa di Gallura (Sardinia). The crossing takes 45 minutes each way. I don't know if all rental car companies permit taking the car aboard the ferry, but I did more than once and fortunately the ferry didn't sink :)
Corsica is more rugged and lush, with high mountains is the middle. Sardinia is a bit drier. Both have beautiful sea and beaches. They are truly a scuba diver and snorkeler paradise.
Corsica (France) is significantly more expensive (both hotels and restaurants) than Sardinia (Italy), even though they are only 9 nautical miles apart.
You will need likely a rental car for both, as public transportation is scant. If you are without a car you will be greatly limited in your ability to visit either. Bonifacio is a beautiful ancient village where a car is not needed, but the beauty of both islands is the natural landscape (both coast and mountains).
I'm not aware of too many tours visiting the places. There are numerous companies operating day boat excursions of the coast and the Maddalena Archipelago (now a marine reserve), but people generally prefer to visit those two islands independently. But I'm sure there might be some companies that do.

I know nothing of this company, I have just heard of it:
https://www.backroads.com/award-winning-tours/corsica
It may give you some ideas for further research.

Kristin, it sounds like you’re looking for the “Back Door” locations of Corsica/Sardinia. I’ve thought several times about spending time on each, but so far have gone just to mainland France and Italy. Well, to Sicily, too, but that brings me to my suggestion.

Rick Steves didn’t have a Sicily guidebook when we went the first time, December 2012, so we used the Lonely Planet book for lodging and sight information. it didn’t present information the way Rick does, but was still extremely useful. Shortly afterwards, Rick published his first Sicily guidebook, and his company now leads tours there, too. So until there’s a Rick Steves book on Corsica and/or Sardinia, Lonely Planet might be worth reviewing.