Please debug this possible itinerary

You need to understand that every change of location eats up half a day, sometimes longer than that if you are island hopping by ferry.
Slow down and take the time to really explore your destinations. Logistics are important on a Greek trip.
Many of us recommend getting to your first island the day you arrive in Athens. Getting over jet lag on an laid back island is way better than facing all the activity and crowds of Athens.
Here is what I would do.
On arrival in Athens find a connection flight to Santorini. It certainly deserves 3 nights. It is close to Naxos so you can ferry there.
Naxos is a great choice. You can easily spend a week there and not see the whole island. Naxos also has excursion boats that go to Delos then Mykonos on day trips. That means you can experience these destinations without having to pay the price of a hotel in Mykonos which is known for being an expensive destination.

Now return to Athens for 4 nights before your return flight.

As for Bugs, I'd have to call Terminix to handle the bugs in this ... and no there is nothing to add -- but much to skip. But Let's get started, because we Do want you to have a successful (and Realilstic) Greece adventure. FIrst: for best help we need to know WHEN. Advice for May or September is far different from Late June thru Labor (heat, crowds, $$). Plus, you only have 13.5 days, IF you arrive by noon, otherwise 13... and for such short visits, most "vets" recommend 2 islands - maybe a day-stop for fleet of foot, and at least 2 full days in Athens. Also, while nice to start AND end in ATH, your time is too short - it takes precious hours to go Into/out of Central Athens & check in/out Twice. ... If you choose flights that arrrive before Noon, we recommend a short flight to Isle #1,.. much nicer to get over jet-lag in lovely, slower-paced isle vs bustling world Capital.

You need places where scooters work, and selective ferry travel (a scooter challenge). You apparently favor scenic & famed ancient sites vs shopping & beaches. So here goes -- To Skip: • Mykonos (daily cruise mob scene, little history) •Delos (paths V difficult for scooter, ferry prob) • Tinos (not a daytrip for u 3). More time in Naxos, 2.5 days max in Santorini. Your plan sequence should be (1) lock in flight logistics (including local); (2) know skeds for suitable ferries, Only then (3) book suitable hotels (free-cancel provision). I hope u are ready to act, because getting well-located hotels, w elevators or main-level accoms, will make trip much more do-able.
(NOTE: I've hotel options at each stop, but share later, because R. Steves has word-limit on postings.

ITINERARY OPTIONS
Day 1 - Arr ATH (Airport) before Noon - 2pm FLIght CHANIA; stay elevator hotel on OLd Harbor
Day 2-3 - Explore CHANIA plus half-day tour of area Highlights (12-psgr mini-bus- excellent) - transfer to Herak for night 3
Day 4 - 9 am Hi-Speed to SANTORINI arr noon; stay in FIRA Day 3 & 4
Day 5 - Hi-Speed Ferry to NAXOS arrive noon. Seaview hotel at Fringe of Port town, level walk/wheel to highlights
Day 6 - 7 Continue Exploring Naxos via car rental
Day 8 - AM flight to ATH.. Car rental by noon -- Drive to MOST beautiful Old-Town in all Greece, NAFPLIO, on tip of peninsula, surrounded by sea, near THE most famed ancient sites -- and only 2 1/2 hrs from ATH airport on modern scenic highway. See links below For photo highlights & superb website. NAfplio Old-town is virtually car-free, all flat lanes to stroll & explore. Best hotel i s right on seafront, 3 floors With elevator & balconies (but a challenge to book!)
Day 9 - 10 - Explore Nafplio & area
Day 11 - AM - return via coast road to Corinth Canal then to ATH by afternoon check into hotel before dinner.
DAy 12 - 13 - 14 -- Athens Sightseeing; for Acropolis, you qualify for disability elevator, but advance booking & constant re-check is vital (and crossed-fingers because it often isnt running). Either boook pvt Guide or use R Steves excellent FREE audio tours)

NAFPLIO LINKS -- http://www.visitnafplio.com/ https://www.flickr.com/photos/visitnafplio/sets/72157626483407223/

Ha ha ... Stanbr & I almost always answer the same posts, with the same advice! The only difference is that he gives the big picture and leaves you to fill it in , while I always somehow wander down into the weeds... My lengthy screed was due to thinking about the dumb details that can slow up the fun, like stairs in h otels & ancient sites, and walkways too bumpy for scooters..

When I read the itinerary planned by chablis1935, I realized they really needed some "debugging." :)

Luckily, Stan and Janet are here to help.

I'll add a few remarks, mainly to confirm that there's far too much island hopping in this itinerary. In my opinion, in two weeks, active and fit travelers can visit two islands and Athens. Anything more is neither reasonable nor worthwhile.

It's also important to specify the travel dates, especially regarding the weather and temperatures. In Greece in July/August and until mid-September, temperatures can sometimes exceed 105°F.

Why take a day trip to Tinos? You need at least five days to visit Tinos, which is particularly interesting for its many small villages nestled in the mountains. With mobility issues, I don't see the point.

For many years, most savvy Europeans have gone to Mykonos to experience this kind of atmosphere and to see movie stars or showbiz personalities. So, going to Mykonos is a good idea if that's what you're looking for:

https://youtu.be/dMpaksY4sTE

The others are either cruise ship passengers or uninformed visitors who believe that Mykonos is the only place where they'll see whitewashed houses and blue domes.

It's also worth mentioning the exorbitant prices in Mykonos, which is one of the most expensive places in Europe.

So, forget Mykonos and Tinos (even though I love Tinos), it will free up some days for other places.

And if you want to see Delos, you can do so on a day trip from Naxos.