Often the companies combine IT operations, or purchase fuel and aircraft as a bloc to achieve higher bargaining power. However, the alliances have been most successful at purchasing invisible supplies and services, such as fuel. Airlines usually prefer to purchase items visible to their passengers to differentiate themselves from local competitors. If an airline's main domestic competitor flies Boeing airliners, then the airline may prefer to use Airbus aircraft regardless of what the rest of the alliance chooses.
Crete, Santorini, and Naxos look quite doable within the 12-day block, but Crete’s beaches are scattered throughout a very LARGE island, Santorini really only has Kamari and Perissá (and some southern coast bays) and Naxos does have nice places to swim. If you choose only to visit those three islands in your relatively short time, you will do well.
Argostoli is the capital on the mid-west flank of the island and is not really a destination itself, that moniker falling to the contiguous beach scene running from Lourdata south eastward to Skala. While development might have caught up here by now, it should still be a pleasant beach scene and focus for a relaxing stay. The Melissani Cave on the east coast is a must attraction and while it can be visited on a day excursion from anywhere on Kefallonia the two villages or Agia Efthymia and Poros are low-key ‘resorts’ pulling in a regular crowd of travellers and may warrant a look-in. The port of Pesada (just west of Lourdata) is the home of the local ferry to Zakynthos (Zante).
That all sounds good though I would recommend Naxos over Mykonos in March as there’s more to see and do there when not beach weather. And if you do decide to do Mykonos be sure there’s a ferry from Mykonos to Santorini for your dates. And same for Santorini to Crete. There should be ferry service but the route starts different times every year so you do want to be certain.
In 2016, Stiniva beach on the island of Vis was named the best beach in Europe. One of the top beaches in Croatia, Stiniva is well hidden from the sea and not the easiest beach to access. It’s either a hike down to the beach or access by small boat, but a spectacular view will reward you for your effort. Although Vis has never really had large tourists numbers, it has become a popular stop for those sailing the Croatian islands.
The almighty church has kept nightlife in check. If you must see and be seen, head to quietly glamorous Astivi or Stoa bar, on miniature Agia Lesvias square, in Hora. Beach life is generally languid and low-key; Psili Ammos and Livadi Geranou are our favourite hideouts. Dinner reservations are essential at Benetos, for Med-Asian fusion on an organic farm, and Lambi for grilled fish on a purple pebble beach.