Your options are going to depend on where you're going in Italy & how many connections you're willing to make. For a 1 stop to Rome you're limited to AA via DFW, A DL-AZ combo of flights via JFK or ATL & BA via LHR. Depending on the ticket for any domestic legs in the US or intra-EU you may be seated in regular economy, an economy plus (generally more legroom) or a business product. Domestic US Economy Plus (or equivalent) tends to be better with legroom when compared to Intra-EU business class but intra-EU business class does have an empty seat next to you.

Take a look at who flies your route, when, with what layovers & through where and then take a look at the options that fit your needs & wants. Each product is a little different. Make sure you know the intricacies of each product. Delta only provides a true Premium Economy product on their A350 but some tickets will sell a comfort+ seat as premium economy which isn't quite the same thing.

Can't advise about the Capital One part.