Euros before we get to Italy

Most restaurants will take plastic, but some will not. It should be easy to find an ATM to withdraw euros from.

Rick's tips on money are here.

It's always more convenient to have Euro before you actually need it. I've never been the type of traveler to rely on credit cards to pay for everything. I believe some ATMs in Switzerland offer the option to dispense Euro, depending on the location. The self-service kiosks in Italy's train stations accept payment by credit card. Most of Varenna's restaurants accept credit cards. There are a few that don't.

Getting them at your first Italian stop should be fine, such as in Tirano, if you have a prolonged stop there. In Varenna, I can recommend the DeutscheBank ATM between Hotel Royal Victoria and Al Barilott bar, or there's another bank closer to the boat dock. Varenna restaurants there are all pretty likely to take credit cards but it's still good to have cash handy everywhere in Italy. Some credit card machines suffer "outages," suspicious or not.

During our past winter trip to Switzerland we took the Bernina Express to Tirano (Italy) from Klosters-Davos and return, stopping in Tirano lunch. The Italian restaurant did not accept credit cards but would take Swiss Franc (CHF) if you didn't have EUR cash. Another person had to dart to the nearby ATM to withdraw 20 EUR to pay their 16 EUR lunch bill.

If I recall correctly, there was an ATM cash machine in the Tirano train station and were several nearby banks.

Everyone agrees the least expensive way to get local currency is from an ATM at your destination. And we do that. But we've always been more comfortable having some local currency in hand when we land. Getting two or three hundred Euros from your local bank will cost a little more, but it eliminates the hassle of trying to find a machine, the stress of hoping it works (they do occasionally malfunction), and doing all that while jet lagged. To us the small amount it cost to have money in hand when arriving is money well spent, and the cost relative to the overall cost of the trip is not, in my opinion, that much. Just something to consider.

I really have never had a hassle finding a machine after I land or come in by train.
Don't see the point in paying more for Euros before hand, I prefer to get as little cash as possible.

I just did a trip to Norway for a week and did not even touch a single NOK, I am still quite amazed I was able to survive the week on plastic alone and never once went to an ATM.
In Italy that just would not be possible since some places/vendors/services are cash only but I still try to use Euro cash as little as possible.

The majority of restaurants take credit cards.