Welcome to this Transatlantic cruise and I think you will find it most enjoyable.
We have been on Oceania for some time and booked this crossing as soon as we saw Jacques Pepin (Oceania's Culinary Director) would be on board. It was fully booked, but after taking a wait-list, we were cleared.
A few years ago, we took an Oceania crossing from Barbados to Barcelona and found it absolutely perfect in all ways. There will be some days at sea, so plan on activities to keep you busy or whatever pleases you.
Barcelona is a fascinating city - perhaps you can arrive early to enjoy it...