Sardinia trip tentative plan.....add stay in Bonifacio, or not?

Yay, eks, you are finally getting there! I wish I could drop some breadcrumbs for you, alas there is no overlap between your proposal and my two trips. I think as a seafood lover you will be quite happy, have a great trip!
I did stay in San Pantaleo but I was the least happy in that area (had a bit to do with the apartment I rented, the resort—esp if it’s the one I think—would have likely been an improvement but we don’t roll that way, lol).
If you do happen to make it into Nuoro, Il Portico was the meal of the trip, for both trips.

Purely opinion, but I’d save Corsica as you could easily fill the time in Sardinia, but if you are just looking for a teaser to decide on a future trip, it could make sense.

This year’s trip was the first time I ever had phone maps send me to a blocked off road, so just a headsup to precheck journeys. For the most part, roads are excellent, where they are not, they are not—or they are under construction. If it weren’t for a partner always ready to drive, I’d not have seen that half of it, so watch for animals crossing the road and such, and prepare to be wowed by the scenery.

Hi, Giangilberto from Milan, just a couple of advice, the first one for me is the most important one, there are some car rental companies that apply restrictions, and in some cases they even prohibit the rental car from taking a ferry, so you will have to check this with the car rental operator you want to use.
The act of taking the car on the ferry must be explicitly authorised by the car rental company in order to avoid possible penalties or even the cancellation of the insurance in the event of an accident. This means that you should always communicate with the car rental agency your intention to take the car on board, there are companies that require a supplement for the maritime crossing and so on.
But the biggest problem could be another one, Bonifacio is not Italy, Corsica is French territory, so you are leaving the country where you rented the car to go to another country, you can drive a rental car abroad, especially within the European Union and some neighboring countries but there are rules and conditions to follow, which vary depending on the rental company and destination.
Almost all Italian rental agreements include restrictions on border crossings some prohibit it, others require written authorization and a surcharge, and insurance coverage may vary.
Due to international political circumstances, for example, restrictions may apply for certain countries or regions, or additional insurance may be required for international travel.
So if your hotel is on the cliffs of Bonifacio and unfortunately your car rental company doesn't let you take the car to France you have to rely on taxis. Taxis have their own rules and above all it depends on the area you are in and they may have to be booked, I don't know what the rules are on French territory but I think they are more or less comparable to the Italian ones. So pay close attention to this aspect because if you don't have a car and, for example, you could have problems with taxis it could be a big problem to have the hotel in that location.
Last but not least check the ferry timetables for the months you are going. Below are a couple of links to companies that operate the route from Santa Teresa di Gallura to Bonifacio where you can find all the information you need:

https://www.mobylines.com/

https://ichnusalines.com/en/

Every time I've been to Sardinia, I've stayed only in the area called Gallura. From there I ventured to various locations but always in the north. A several friends who have vacation homes in Sardinia told me the north half of the island is the most beautiful, so I followed their advice, but I can't really say whether they are right or not, since I don't know the south. For sure, if you go to the north, you should take a boat excursion to the Maddalena Archipelago national park, it's really worth it. The excursions do not operate with high winds (which are common in the strait of Bonifacio) so book early, and in case of high winds, try again the next day or so. Capo Testa and the Valle della Luna was also nice.

I've been to Bonifacio and southern Corsica once, via ferry from Santa Teresa (50 min crossing). At the time I didn't know you had to ask for permission from the rental company before doing so, so I didn't, but you should, as taking the car on a ferry or simply across borders without permission is a breach of contract that might invalidate your insurance coverage.

Once you get all permissions, when you go across, certainly visit Bonifacio for a day on the way there or before ferrying back to Sardinia (beautiful medieval fortified town), and if you venture out, consider also nearby Porto Vecchio. There are many coves and beaches in Corsica, so that you can enjoy some beach time too. Your hotel seems to be up the hill above Bonifacio, but not really on a cliff.

I've been to both Sardinia and Corsica, and have been pretty much all around both (have driven all the way around each of them). They are two of my favorite destinations in Europe or, well, anywhere. We spent 18 days in Sardinia, 14 days in Corsica. When departing both of them, I found myself wishing I had had another week or 10 days, but that seems to be a common feeling I have.

A quick scan of your plans tells me that you have avoided the mistake that it seems nearly everyone makes: with few exceptions, most folks coming here to post questions about these destinations seem to think they can knock out one or both of them in just a few days. To me, that's as unfortunate a choice as planning to see France or Italy in a few days - or trying to squeeze them BOTH into a 10 day trip. So good for you, you have made a wise choice to dedicate a few weeks to Sardinia. You will be glad that you did.

I think it's best to stop thinking of these as mere islands. They're like separate countries. Not exactly Italy, nor France, but a fascinating mix of multiple cultures and their own indigenous charms. Each deserves a good chunk of time to appreciate, like any country.

One of the big questions is whether or not to include a stay in Bonifacio.

I'd say the answer to that is: it depends.

Bonifacio is indeed highly swoonworthy. But so is Cagliari, Alghero, Bosa, and a half dozen other places scattered inconveniently around this large land mass. And so are a handful of places scattered just as inconveniently around Corsica. Both are bigger, more diverse and more interesting than I think most visitors expect, and it just takes more time than one might imagine to get around to all the good stuff.

But is Bonifacio worth a stop? Hell yes! Look...

But there's lots more around Corsica that's worth a stop, too - look...

Of course, Sardinia has plenty to love, too.

You have made the wise choice to give Sardinia the time it deserves. Do you plan to do the same for Corsica? Because while Bonifacio is awesome, IMHO it would be a shame to just pop over to Bonifacio but never go 'round the rest of Corsica. If Bonifacio whets your appetite for Corsica, then sure, carve out a couple days from your Sardinia trip (but be careful, there's so much to see on Sardinia, and each day you take for a "side trip" pulls you away from the other good stuff you might be skipping). It's the ever-present tradeoff we all make when planning any trip: do this, or do that...only you can decide if it's "worth it."

To your specific questions...

Yes, there are significant ferry/car rental questions to sort. It's a ferry not just to another island but to another country. IME many car rental contracts contain a boilerplate "no ferry" clause; often they will waive this if you simply ask. Or shop around. Or maybe just do a foot ferry?

Is the town totally given over to tourism?

No more so than Cagliari (which is not to say either has been ruined by overtourism). Both get cruise ships, evident during mid-day, but using the usual strategies (be up and out early, savor the mornings and evenings, find someplace else mid-day, etc.) one can avoid the worst of the OT. I LOVED Cagliari.

In Bonifacio, we stayed at the Hotel Santateresa. It was jaw-droppingly spectacular. Our room had a balcony overlooking the cliffs and the sea beyond - we could see Sardinia in the distance. I don't recall how expensive it was (we paid with loyalty points so zero out-of-pocket) but we absolutely l-o-v-e-d the place and I'd stay there again in a heartbeat. Quiet and private, but just steps from incredible scenery, a 5-10 minute walk from the center of the city - perfect. I can still remember, the place smelled like honey. Mmmmm. You can see the views on their website.

Include excursion to see flamingos.

Not sure an organized tour is needed to see the flamingos. We saw them in several places, just pull off the road and gawk.

Of the places you mention, we loved:

• Cagliari - My new Italian crush. ★★★★★
• Santa Maria Navarese - Very pretty coastline, but not a lot to do or see beyond the seashore. maybe we needed to spend more time there. ★★★
• boat trips to Baunei coast - We did not go there. We DID hire a boat from Cala Gonone and spend half a day exploring the rocky coast, snorkeling, and gushing over the scenery. Lovely! ★★★★★
• Bosa - Cute, charming city with no crowds (we were there in late September/early October) ★★★★
• Alghero - Charming, authentic, uncrowded seaside city. ★★★★

I am sure you will love your time there. Very special places.

Hope some of that helps. Cheers.

I'm overwhelmed by the outpouring of comments, and information, here..thank you all very much!!!

The more I delve into this plan, the more I realize just how large and varied is Sardinia, and by how much, even with three-weeks-plus, I will be forced to leave out!!!

I have to contact a few rental agencies (my preferred is SIXT) and inquire about taking the car on the ferry and into a second country. Although we could also leave it for a few days (somewhere??) in Sardinia, I did read that taxi prices in Bonifacio were extraordinarily high, so I think taking the car would be good and we could then do a day trip or two...

My next step is to write to the hotel I had picked out, in Bonifcio, and ask a few questions. I do think that it would be best to leave Corsice for another trip when we could just stay on that island but, realistically, I'm not sure that that day would come because there are a few other destinations we want to visit together before my partner hangs up his traveling shoes. So maybe just dip our toes onto the island is better than not, right??

I'm going to work to refine this plan and return with more questions.....you've all been amazing with all the info you've gifted to me so far!! Thank you, again!!!