What is appropriate dress for traveling in Turkey?

That is absolutely not necessary, although if you really feel the need I suppose you could. There are tons of tourists there from US as well as all over Europe and everyone dresses pretty much normal. If you want to go in to a mosque there will be restrictions, but that is all. There are also Turkish people who are not Muslims. I also want to respect other religions, cultures, etc. but I do that by respecting the people and of course, follow the rules in any place of worship. You are going to love Turkey... it is amazing and the people were incredibly friendly.

Hello,

I'm from Istanbul, Turkey and your question made me smile. I assure you that you absolutely do not need to cover your body in Turkey, only except visiting the mosques. Turkish people wear like what Europeans do, there is no difference just some religious women covering their heads. You will totally be ok, do not worry. Besides, you are coming to a European Union candiate and a SECULAR country. Noone can take your freedom away from you.
A small tip about showing respect to Turks: Learn a couple of basic Turkish words with the true pronounciation, like hello, thank you, excuse me, please, goodbye etc.

Have a good trip.

Alp's words of advice are perfect. I had my arms and legs covered the entire time, but that was because it was very cold when I visited! If you are a woman, do cover your head when entering mosques, but other times I wouldn't worry too much. I dressed modestly overall, but you will see all types of dress there.

When I was on an RS tour a few months ago, in cool weather, I asked our guide about that. Of course everyone was wearing sleeves and long pants then. She said that in warm weather, many women dress as skimpily in Turkey as anywhere in Europe.

I was in Turkey late August/early September last year, during a heat wave, and I assure you that there were lots of shorts and sleeveless shirts. If you go to a mosque and are not wearing appropriate clothing, they have scarves (and once even a wrap-around skirt) to lend to you.

When you are in public, it's fair game for people to look at you, address you, or make comments, so a somewhat modest standard of dress can make you more comfortable. Dress standards on a beach in Turkey will be the same as on any beach. When not on the beach, short sleeves and capri pants are still better than no sleeves and shorts, without going all the way long. But you'll be recognizable (and welcomed) as a tourist no matter what you wear.

In hot weather I would rather be in a lightweight, light-colored UPF 50 shirt with elbow-length sleeves than a sleeveless shirt and sunscreen. And a light cotton skirt, even a maxi, is cooler than shorts.