Antalya and Fethiye

Oh no!You had an interesting trip lined up Ahmd...what happened?Sorry to hear you had to abandon it :(
Okay so,Antalya and Fethiye.I would say you have got the days balanced about right.
In Fethiye there are boat trips to Butterfly Valley and also another trip called the 12 islands boat tour too,no history on that just a nice lazy day out.You can get to both Ölü Deniz and Kayaköy by regular local minibus.Tlos and Saklıkent are best done with a tour to be honest unless you are thinking of hiring a car,similarly Pinara too.Perhaps you may also have time to take the bus to Patara which is an hour from Fethiye and very nice.

For Antalya set aside a day for the excellent archeological museum and a wander around Kaleiçi,the old Ottoman quarter and Düden waterfalls on the road to Lara Beach are very pretty.
You will see plenty of tours covering Aspendos,Perge and Köprulu Canyon,and,given the distances involved plus infrequent buses,a tour makes good sense.
In addition also take the bus to Side one day which is nestled around some lovely sea front Roman ruins.Side Museum too is worth as look.
Another day you could head west to Kemer and take the teleferik up to the top of Mount Tahtalı,stunning views!
http://www.olymposteleferik.com/en/home/
and perhaps even visit Olympos ruins whilst out that way.
You could also consider taking a day from Antalya and one from Fethiye to allow a couple of days at Kaş to take a boat trip to Simena and Kekova sunken ruins and a bus to Demre with it's stunning rock tombs.This would help you to get even more from your time here without it feeling rushed.

Thanks for your comprehensive advice. I might do this trip to Fethiye, Kas and Antalya in the last 2 weeks of August. I might add along to it the first 2 weeks of September (take advantage of milder climate) to see NE Anatolia (Kars, Ani, Dogubayazit, and Erzurum). On my way I will also want see Mt Nemrut through Malatya. I know it is better to get to the site from the south but that will be along deture

How long do I need to see these places in NE Anatolia? is Yusufeli worth a visit. I am NOT going to hike or explore the mountains around it

Ohh,another month here :)Well,if this is what you are considering then I would say to switch these two area's around.
That north east corner is mountainous and therefore a few degrees cooler than the south coast so going there is August would be lovely.
Furthermore as you can imagine August is the very peak of high season and the coast will be like.....sardines in a can!But if you go there during early September then you will find it slightly less busy.Firstly there will be hardly any local families left;most will have returned for school starting,similarly far less foreign tourist families too.So it will of course still be busy but at least the sardines will have some room to move ;o)

2 weeks in the north east would be great,perhaps you could slot Trabzon/Rize area in there too.On arrival here consider flying on directly to maybe Adıyaman or Malatya for Nemrut as the start of your tour.From Malatya you could join up with Güneş Hotels tour if you ,they would then return you to Malatya from where you can take a bus to Erzurum and onwards.
Yusufeli is worth a visit as it is set in wondeful scenery even if you don't intend to go mountain climbing.

To then get back down to the south coast consider finishing in Trabzon from where Sunexpress have direct flights into Antalya several times a week.Save yourself a very long bus ride.
Alternatively,as you will have a bit of time,you could finish in Kars or Erzurum and take the Doğuexpress train to Ankara and then bus or fly from there down to the coast.This is not just a train ride this is a wonderful experience!

So that has given you a few things to think about......

Thanks a million. You made the trip far more interesting and more manageable. I was little bit sheepish given the expected high temperatures and distance.

I am assuming that there is little need for advance hotel prebooking esp in the north east

What is your forcast ...ummm .... for Mosquito??
:-))

You should be fine for hotels in the north east but for the coast,best to book in advance.You probably could just rock up and find a suitable hotel but in the heat would you really want to trawl the streets with luggage looking for somewhere?
Ahh,mozzies(God rot them!)in spite of the rich greenness of the northeast there isn't such a bad problem with them-probably because they will all be on holiday along the south coast haa haa haa!You will see a few around in the north but on the south coast they are a total pain so buy some mozzie spray when you arrive here,especially if you have an allergy to mozzie bites or if they find you particularly attractive.

About Kas, can I do it as a day trip from Fethiye? Or even a tour from Fethiye. At the most I can spend a night in town, if I really have to.

I would rather do it as a day trip. Or do it on my way from Fethiye to Antalia, if I can store my bag in the bus station.

Hmm...um..um yes...you could do it as a day trip from Fethiye but it is a 2 hour bus ride each way so it wouldn't give you long there.To be honest, a few short hours would not do this lovely town justice.There is much to do and see around there so ideally try to have a long overnight stay or even a couple of full days.IMHO,if necessary cut a day off Antalya or Fethiye to allow extra time for Kaş,it really is that lovely :)

I had a little bit of a rough year as I had to postpone all my vacations because of personal and family reasons which -Thanks to God- have been resolved. So I am resuming my plans to take the Mediterranean cost trip on the next few weeks

I am assuming that tours to Tlos, Saklıkent, Aspendos,Perge and Köprulu Canyon are NO longer operational due to winter
No boat trips. Kas is probably NOT worth the visit in winter
I am adding 2 days to each town so I will spend 6 days in Fethiye and 9 in Antalya to make the above itinerary doable

Any comments will be appreciated , Winter might NOT be the perfect time but this what I have

there are couple of interesting threads that were useful about winter in Mediterranean coast

https://www.lonelyplanet.com/thorntree/forums/europe-eastern-europe-the-caucasus/turkey/12-day-turkey-intinerary-suggestions-please?page=1#post_21850752

https://www.lonelyplanet.com/thorntree/forums/europe-eastern-europe-the-caucasus/turkey/fethiye-urfa-mardin-istanbul-an-update-in-november-2014-ef5b8c3e-3c69-4824-8c85-6d1a600e2980