[Effendi]

If you first visit Italy you can buy a Wind prepaid card with the Call Your Country Option (free of charge for new customers) with which you can call the US at 35c€ per minute (normal rate would be 50c€/min). If you plan to use data you can activate one of the several data options like Mega300 (8€ for about 100MB of data per month, in Italy).
While in Switzerland you'll pay 0.80€ to call the US and 0.35€ to receive (all rates per min, billed by the minute) and data will cost 0.0125€/KB. In Italy Wind has 3G coveraga in all bigger towns, and in Switzerland it can roam on the local 3G nets too.

If you want more 3G coverage in Italy you can buy a 3 ITA card which also has a good data offer (Naviga3, 50MB/daily for 9 euros), but higher rates in Switzerland.

Good for roaming could be Vodafone with the Passport option (1€ for incoming calls up to 30 min and 1€ first min plus normal national rate for the following mins for outgoing calls).