OK. When you redeem Avios, you are charged extra for each flight flown. By contrast, AAdvantage redemptions include necessary connections. If this were a simple intra-European nonstop flight on IB, an Avios redemption would almost certainly be cheaper.

I see that Iberia partner Vueling flies BCN-ZRH nonstop, so that might be a cheaper IB Avios (not BA Avios) redemption or cash option. But Vueling is not an AA partner, so you cannot check Vueling award availability on aa.com, or credit Vueling cash flights to AAdvantage. And Vueling is all Economy Class, so it might not suit your needs.