I just thought I'd offer some tips for visiting this amazing, beautiful, friendly yet sometimes frustrating country.
Before even booking a holiday check out the entry visa requirements on the Ministry of Foreign Affairs website http://www.mfa.gov.tr/visa-information-for-foreigners.en.mfa
If you have any doubts at all contact the Turkish Embassy where you live.
Things here can change quickly so never assume anything. Also different officials may have different knowledge. If you are friendly towards them they are usually far less officious.
Allow time to buy your visa at the entry point and do not overstay the visa. The penalty is a fine calculated on the days you are over and a ban on entering Turkey for several months.
Be friendly where ever you go and you will get an enormous amount of help.
Change your mney here in Turkey - a better rate of exchange so just bring enough for the first couple of days of your holiday. The currency is Turkish Lira but you will see prices in Euros and most currencies are accepted. Make sure you have a good idea of the current exchange rate if paying in money other than lira.
Transport around is excellent. Great bus services from city to city and within cities dolmus (mini buses) or regular buses and in larger places tram ways. Taxis are plentiful and not too expensive.
Make sure you have adequate health insurance as health care is not the cheapest here in an emergency. However that said denistry is a lot cheaper than for example the UK and of a very high qualty especially for cosmetic work.
Lots of shopping opportunities from designer "fakes" such as clothing, handbags, sun glasses to beautiful leather and of course the gold.
More than anything - enjoy yourself :o)
I will add to this later