Marmari
Marmari is a tourist village on Kos' north shore that is comparatively peaceful.
The best part about Marmari is that it contains everything a traveler could possibly need. Supermarkets, car rental agencies, ATMs, dining establishments, and tavernas are all located right on the beach, making it ideal for a group vacation without constantly being crowded.
You can be on the beach or in the pool in no time at all with transfer timings from Kos airport ranging from 20 minutes to little over 30 minutes, depending on whether you are the first or last drop off.
There is a decent choice of hotels, the majority of them are located near the beach. There are also smaller apartments and spacious all-inclusive resorts with kid-friendly pools. It is important to confirm the hotel's precise location before making a reservation, as some, especially the larger hotels, are not usually located in the town proper but rather along the beach.