Should I get euros before I leave the US?

No — US banks and airport exchange counters give you a worse rate than an Italian ATM will. Land, walk to a bancomat inside an actual bank branch, and withdraw a couple of hundred euros. Bank ATMs beat the standalone machines in tourist areas, which charge high fees and push bad conversions. Take out larger amounts less often to reduce per-withdrawal fees, and use a debit card that reimburses them if you have one. The only argument for pre-buying a small amount is peace of mind on arrival, and it costs you maybe $15 for the comfort.