I stayed in Kardemena when I was in my early 20's and loved it - the beach was gorgeous, there were loads of bars and boys ( ) and late night clubs. It was a very busy, bustling resort. Obviously that was 16 years ago but (and this is just my opinion) I wouldn't go back at my age now, I think it's a young persons resort.
Can't really comment on Kos Town as we only visited for the day but the promonade and harbour are lovely.
If you're looking for something a bit more low key have you thought about Kefalos? It's quiet and relaxing with more traditional tavernas.

Puddleduck is spot on. Although Kardamena is not in the same league as Kavos or Malia its still a major young peoples resort, of the two definately Kos Town. We also chose Kefalos for our last Kos holiday and really liked it.

Hi Puddleduck and RDV. Thanks for your replies. I didn't think Kardamena would be really busy with 18-30's in early June . Our main priority is our son (who is just 12). Will have another look to see what's on offer for Kefalos .

you might like to look at www. greekisland.co.uk
it has a good accurate overview of the Kos resorts

You also might like to consider Mastichari - HUGE beach, quiet, close to the water park, day trips to Kalymnos....

Hi all. Think we have decided on Tingaki (Ilios or Fili apartments). Any comments most welcome . Gx

Good choice, friends had their first Greek holiday here last year with children aged 15 and 16 and they loved it, very handy for Kos Town without the need for a car.

Hi. Some friends (without children) recommended Kardamena but after looking at the map of Kos, I thought Tingaki looks better placed for other resorts. Gx

well we are a bit older than your children but we are off to Kardamena next month it has something for all ages..

wizard

pm Shirley H for info on the Illios. Having been to both Kos Town and Kaadamena I don't think you would go far wrong with either. We went to both with small children & teenagers & had a ball.

I agree with Helen T. Stayed in Kardamena about 3 years ago and Although it did cater for young adults none of us felt out of place. It was the type of resort that suited all ages. We were there in September and I think that since you're not going to be holidaying July/August it will have the same kind of feel.
We stayed in the Illios Tingaki when our son was 15. It was the last holiday he took with us (too grown up after that ). He had a great time. There was music played around one of the pools, there was a large screen t.v in the lounge area along with a quiz machine and it wasn't too far to walk to the shops and restaurants. We also hired bicycles and my husband hired a scooter which was easy too drive as the roads weren't too busy.
Kos town is lovely with loads of shops/bars and restaurants, as well as a pretty harbour. You've definitely made a good choice with this island and you won't go wrong whichever of these resorts you choose.