Help with Sardinia and Sicily itinerary

It’s kind of a short time if you want to visit both islands.
You also need to check the availability of non stop flights off season. There are many options during the time schools are closed, June through mid September, but not as many outside of that period, the largest airports are Cagliari and Olbia in Sardinia, or Catania and Palermo for Sicily. You can check the Wikipedia articles on those airports to see how their connections and the airlines which serve them.

There are many past posts about Sardinia or Sicily. Use the search box above and start browsing.

I wouldn't try to fit in both Sicily and Sardinia in such limited time, you'll waste a day travelling between the two. They are both large islands with a host of places to explore.
Late September - go to Sicily - maybe a couple of bases, the weather could be a bit better and it's an ideal time of the year especially for places like Ortigia, Ragusa-Modica-Noto and Trapani with maybe a boat trip to Favignana etc etc
https://slowtravelitalyspain.blogspot.com/2019/03/trapani-october-2016-trip-report.html
Mid-May - go to Sardinia and explore the north - the nature is fantastic that time of the year with flowers everywhere! Maybe two bases - one south of Olbia for the beaches and the other could be Alghero for Alghero - Bosa, Stintino, Castelsardo etc

What about this idea, is it too ambitious? Fly from US to Corsica and stay in Porto Vecchio, day trip to Bonifacio. (4-5 nights) Fly to Sardinia and stay 6 nights (not sure where). Fly to Paris for last 5 night then fly back to US. Car rental in Sardinia only.

I see I can ferry from Corsica to north Sardinia in less than an hour.

It's your trip and you need to make your decisions based on your own priorities and the time you have. This is always true when planning any travel - all travel planning is always about trade-offs and priorities. That said...

I spent years casting an eye over Sardinia, Corsica and other large Mediterranean islands, trying to figure out how to squeeze them into other trips to Europe, as kind of a side-show. As I explored my options, the more I drilled down into what all these places appeared to offer, I kept running into the same problem: these are big places, they have a LOT going for them from many touristic standpoints: jaw-dropping scenery, rich histories, unique and complex cultural mixes, appealing cities and surprisingly attractive natural places. They may look small to us from far away, but they are big - bigger than most people expect, and it often (usually) takes a lot longer to get around and see them than we often expect.

Finally, I broke down and had to admit to myself that they were places that deserved more time than I could really give them as a "side trip" to Italy, France or somewhere else. I once "did" Sicily in less than a week - and looking back, that was crazy. I wasn't going to make that mistake again.

So I planned and made a trip to Sardinia. Not half of Italy with a side-trip to Sardinia. Just Sardinia. It was one of my favorite trips ever (to anyplace). I spent almost 3 weeks there, could have used another week or two to really get it all, but my 18 days there were absolutely wonderful (though we were still moving pretty fast and we could have benefited even more if we could have slowed down further). Bliss.

Last fall we did a similar trip (of about 2.5 weeks) around Corsica. It was also wonderful, again we were still moving a little faster than I would have liked, it was obvious we could have enjoyed it even more if we had had another week or 10 days there (we still had to blow past or through places I could tell were amazing), but in the end, I was sooooooo glad that I had not tried to squeeze it all in during a larger trip to France or tried to do Sardinia + Corsica together on a short trip (but hey, if you've got 8 weeks, that would be awesome).

Many on this forum urge visitors to s l o w......d o w n. It is a lesson I keep re-learning on every trip.

Now, we all have to make choices and few of us have unlimited time and money. So if you need to make a trip a blitzkrieg, sometimes you just gotta do what you gotta do. For me, the answer came easily, eventually (I'm stubborn). That was to just bite the bullet and plan separate trips there.

So - to answer your question directly - from someone who has done all three of the large islands you are looking at (two on extended trips dedicated to those places, and one as a short "side trip" from Italy) my advice would be simple:

Pick one, and do that one right. You will not look back and regret it.

We did Sardinia one year in mid-September to early October. It was perfect. Another year (last fall, in fact) we did Corsica in the same time-frame. It, too was about as perfect as I could have hoped (although in both cases, they would have been even more perfect if we had had another week to 10 days there). I think each of these large islands deserves a MINIMUM of roughly 2 weeks if you want to have a chance to see most of them.

If it helps, think of them this way: Sardinia may be part of Italy, and Corsica may be part of France - at least they are technically, nowadays. That has not always been the case, and may not be the case in the future (all over Corsica, we saw graffiti declaring: "Corsica is NOT France!"). These islands are, in many ways, still separate entities, like nations of their own. They have so much to see, do and enjoy. Do yourself a favor and give them as much time as you can - just like any other European country,

I hope this is helpful in your planning and prioritizing.

Thanks David. This really makes me think. We did a trip to Portugal last year and in 19 days, did 5 trains and 5 cities and it was too much toward the end. We are used to being on the move but the idea of islands is to explore and relax. I am not sure if I will give up the notion of visiting both Corsica and Sardinia as this could be my last trip to Europe, but I can forgo Paris as we have been there before. I think I can still see a lot with 8 - 9 days per island. We would not be attempting to cover them entirely in terms of geography but could see enough to get a good feel. I do love Paris thought! thanks for your post.

Yes to all of your reply. In addition to limits on money and trip time, our days are numbered, too, so we all eventually struggle with that long bucket list and our projected life-spans.

8 or 9 days per island will give you a chance to see some (but not all) of them geographically speaking. So yes, it's doable, but it will bring some hard choices...

As you correctly pointed out, it's a short ferry ride between the two islands. In fact, from our hotel window in Bonifacio we could easily see Santa Teresa Galluria in northern Sardinia (I was reminded of the parking tickets I got there...). The simplest and most logical way to try and combine the islands would of course be to do the southern half of Corsica and the northern half of Sardinia. And there's a lot of fantastic stuff in those places. But the fantastic stuff is not distributed that way. On Corsica, some of the places we loved the most were up the west coast, and in the north. Of course, Bonifacio is beyond fantastic...but other stuff that's also soooo good is further away. Likewise, in Sardinia, lots of wonderful places are in the north, but dammit, they put a lot of the other fantastic stuff scattered around elsewhere (I nearly swooned over Cagliari, and lots of other places in the far south). So there's that eternal dilemma of travel planning: you're gonna be right there, there's gob-smacking stuff just an hour or three down the road...and you're going to have to skip it? O, cruel fate... For me, the answer was (and is) to just plan a longer, more dedicated trip. But I understand that's not right for everyone.

Yes, after about 18 days or so, we too start running down, our batteries don't fully charge as quickly, and at the end of a trip it starts to take more effort to do things, so I know exactly what you're talking about. Me: "Honey, lets go climb that bell tower - great views!" Her: "You go ahead, I'll wait in the car." Earlier in the trip, she would have raced me up the stairs.

As I said, it's all about prioritization and making trade-offs. Sometimes those are tough calls, and only you can decide what's right for you. I often end up re-learning things I thought I already had figured out.

Both Sardinia and Corsica are awesome (way better than most around here would expect). Shhhhh.

Note: I'm still trying to figure out how to do Crete and some remaining large Mediterranean islands. ;)

Sardinia and Corsica is more reasonably doable. The two islands are very close and you can visit both in two weeks. Sardinia is kind of big, but the best part is probably the northern side. I’ve done so (flying to Olbia, Sardinia, from Italy) then I took the car ferry across from Santa Teresa di Gallura to Bonifacio, and after a period in Corsica I went back to Sardinia. You can do the same and I’m sure there are plenty of flights from Paris to Ajaccio in Corsica. The ferry from Santa Teresa to Bonifacio is about 50 minutes. Sardinia is definitely cheaper than Corsica, but both are beautiful with beautiful beaches and natural landscapes.