I've been to both.
Halkidiki is more peaceful than Kos and has some beautiful scenery. We stayed in Polychrono which is just along the road from Hanioti and we popped down there a few times for dinner - there's lots of choice of places to eat from English pubs to traditional restaurants. We hired bikes one day and went on a cycle tour which was really good fun. You can dive there but visibility isn't that great. I think it's a lot quieter than other places in Greece.
The las time I was in Kos I was in my 20's! so someone who's been there more recently will be able to offer you more up to date advice. I think there'd probably be more to do on Kos. Kos town in particular is a nice day out and you can catch ferries from there to other islands.

Anyway, here's the offical Halikidiki tourism site - http://www.halkidiki.com/english/index.htm
And here's the Kos one - http://www.kosinfo.gr/
Have a quick look, might help you make up your mind

Hi Puddleduck. Thanks for your reply. Trying to get hubby to change his hols so we can try for Thassos (which I think are Sunday flights). He has booked Thurs/Fri off cos I wanted to go to Samos (Thursday flight) but there is absolutely nothing available for Thursday 31 May and the only alternatives were Kos and Halkidiki. I fancy Hanioti. Will let you know where we end up . Gx

Hi Pargaluvva, Thomson have holidays to Samos available on 31st May.

Hi Grecofile. Had already checked Thomson and Kosmar and nothing available . Looked again after your posting but still nothing .

have a look at fleetway travel

wizard

Hi Wizard. Checked Fleetway Travel - nothing for Samos or Thassos. We can get Thassos from Newcastle but that's too far for us to travel . Looks like Kos, Halkidiki or Ibiza. Gx

sorry but always worth a try...we are off to Kos in 4 weeks or so

Hi Wizard. Which is your favourite resort and why? Thanks in advance. Gx

I got my Thomson Kos Town holiday cheaper from the First Resort website than Thomson could offer, I searched long and hard for my holiday - coming up on the 19th May and First Resort was definitely the cheapest.

http://google.thefirstresort.com/channels/index.asp?branded_specialoffer=TFR%20LATE%20DEALS&Partner=1491

sorry just back from a weekend up north [took the Pendle Witch home to visit the rest of the sisterhood]

we go to Karhdamena being old fogies we can have it quiet or go out and boogi with the youngsters, the island isnt large which makes it a great place for touring the isaland

wizard

Myself and My family have visited Halkidiki at Whit Half term for the last few years and possibly this year too.

We love Halkidiki as it is green, hot, beautiful and people are friendly.
We always get a late deal to a four star s catering hotel for two weeks and considering we have two studios as there is five of us, we only pay just over a grand!

We found Halkidiki to be cheaper than Rhodes and not commercial.
Also all the local supermarkets had absolutely everything you could want too as it classed as the mainland.There are lots of last minute deals to halkidiki at the moment for in a few weeks you just have to look.
Lots of Greek and Italian tavernas, no McDonalds in sight.

We stayed in Rhodes at The Esperides Beach back in 2004 The Hotel was great , and Rhodes Old Town was nice but we thought apart from that the kalithea/Falaraki area was just a line of Bars and Pubs.Although I have heard Pefkos and Lindos are nicer.

We did want to try Parga this year but the hotel I had my eye on there had already gone for whit (Dracos) but try next year maybe.
Oh nearly forgot Halkidiki is hotter than Rhodes However its harder to get a tan in Halkidiki, dont know why? strange! The Equator Maybe?

Sorry before you ask what drugs Im on, My refferal to Rhodes was because Kos and Rhodes are near each other with similar weather and landscape, and so might give you an idea what kos is like.

Hi all. Thanks very much for your replies. We have managed to get a week in Thassos . Really pleased cos didn't really fancy Kos or Halkidiki.

why didn't you fancy Kos or Halkidiki? What has put you off them?

I can't understand anyone not wanting to try Halkidiki, its great in fact Im off on the 24th May to Halkidiki with my family for the third time!

The weather is great the people are great.
What more could you ask for?

Hi there Karen and Bunny. Kos sounds a little too commercialised (although I am not saying I will never visit) and the transfers for Halkidiki were too long (and also I have heard that Hanioti (where we were thinking of staying) is a bit of a 'man made' resort. We have booked Thassos and the only other Greek island I would really like to visit is Samos so maybe in a couple of years we will try Kos and Halkidiki.

Oh yes I forgot about the long transfers- they aren't that bad can take an hour to two depending on drop offs. Usually isnt too bad taking in the scenery and seeing to the kids.
Have a nice holiday!
I'll try parga soon and you can try Halkidiki next time!

Bunny. You will love Parga. Also try Stoupa and Lesvos. Gx

I know why people say that about Hanioti, but I found it to be a really nice chilled out place and was in a good location (easy to get to other resorts) and close to a good beach.

I am going to Kos on Saturday so I'll let you know what its like I think some places might be a bit commercialised but I think the resort I am going to is quietish.

Enjoy Thassos!!!!