We are spending 4 nights/5 days in Istanbul this October. Just wondering if anyone can give us insight on how much Lira to take with us. Or is using the Euro a better option? We will probably charge any large purchases (if any!) on credit card and just use cash for small meals and souveniers. Not sure how much meals/drinks costs... Thanks!

Don't take any Turkish lire with you. ATM machines are ubiquitous, especially in the tourist areas. Pay for your visa in euros or US dollars. Do not count on using any other foreign money for the visa and there were no ATMs on that side of the passport control (this may be different in Ataturk airport). One Danish woman was stuck because Turkish immigration would not accept Danish money and she had no way of getting lire or euros before getting through immigration.

No ATMs at Ataturk until you have cleared baggage claim. They're in the terminal.

Use ATMs. I traveled all around Western Turkey and got cash (Lira) from ATMs. It is so simple. Why pay more to get Lira at home. You can't spend it until you get to Turkey.

The atm machines in Istanbul and Goreme give you the options of Euro, US $ and Turkish lira. I don't think all of them do but the ones in major tourist spots do. They were fine. I had no problem with them.
Cash is king in Turkey. You can ask for a discount (and don't feel bad about it) when you pay by cash. That goes with hotels too.