When booking a holiday to the island of Kos (which I would highly recommend), forget all of the others towns on the island. Kos city is the definitely the prettiest, biggest, and most fun town on the island, offering a variety of activities to entertain you. Do pick a hotel on the outskirts of town to have peace and quiet at night. Well connected to the rest of the island through bus lines, bicycle lanes and motorways, and well connected to other Greek islands and Turkey through the gorgeous harbour and marina. There are more bicycle rentals than you can count, and I would highly recommend renting bikes, cycling within Kos and its surroundings, to the Asklepeion or the hot springs, is a very enjoyable way of getting to know the island. Kos has a broad offering of bars and restaurants, and for cheap groceries there's the Carrefour. The boardwalk besides the sea, all the way from the marina to the harbour, is a gorgeous walk in the early morning.