The currency rate to exchange your home currency is better in Turkey, but it is recommended that you change the currency to the official currency in Turkey which is Turkish Lira. Most of the establishments, restaurants, shops, and hotels will accept only Lira and therefore it is the main currency that you can use across on your Turkey trip.
While some of the shops and hotels do put up a board that they do accept Euros as well, but the exchange rate may be at the discretion of the retailer or the hotel owner. It is important that you exchange the currency at various international airports and banks to get the best exchange rate.
You can also bring in your credit cards and debit cards that are widely accepted all over. However, make sure that you do talk to your card company over the charges deducted for withdrawing funds in Turkey.
Speak to SOTC if you have any queries regarding Turkey holiday packages.