We are spending the day in Ephesus and are wondering if we need to use Turkish lira or if Euros are acceptable.
Euros are not acceptable.
Use your credit card, or use local currency. You wouldn’t expect to use British pounds in the US.
The Turks would love to get Euros because their own currency is in such downfall (this would be true of any country experiencing high inflation and currency free fall), but try to resist any such suggestions. You will get a poor exchange rate of their own choosing if you use non-Lira currency.
I booked a transfer from the airport to the first hotel of our upcoming RS Turkey tour through the hotel. They wanted payment in Euros in cash on arrival at the hotel. I don’t know how common this is, but it looks like I’ll getting some Euros at our transfer in Amsterdam. Ending the trip with a few days in Samos, so I’ll have a chance to unload. That said, I plan to use my card whenever I can.
There are towns in Turkey where Euros are widely accepted. We saw this in Kusadasi, which is a big cruise ship port. Vendors in the shopping area near the port showed signs in Turkish Lira, Euros and Dollars. Some were surprised when we had Turkish Lira for our purchases.
And yes, as noted above, I'm sure any currency rounding favored the vendors.
Some heavily touristed areas will accept Euros (or dollars, for that matter), but I wouldn't count on it. Often, though, the price advertised in Euros is much higher (maybe 30%+ higher) than the price in lira. They are betting that you can't or won't do the conversion in your head.
Stick with lira, if you can.