Spain

'Any ideas?' - What do you mean? Do you mean other ideas? Or do you want someone to make your mind up for you? For elimination - a day trip to Morocco will certainly not find Morocco, but Tangier from Tarifa. The city of Tangier is an industrial port city which could be almost anywhere and is unrepresentative of Morocco, if that is what you look for. You give no indication of your experience of Spain. Nor how long you have after being in Barcelona for a week (too long for me, but you are not me). Nor what time of the year - if high summer there is little likelihood of 'sleepy little beach town'. Based on possibly too long in Barcelona, I cannot tell whether you 'don't have time for both'.

Tarifa was nicer than I expected but Granada has more/better sights. We didn't take the ferry to Tangier. For me, it would be like going to Tijuana and thinking you've seen Mexico.

Just passed through Tangier a few weeks ago, and honestly can't recommend it. The real Morocco is further to the south. The Tangier day trip to me seems overrated, especially with the amount of effort it takes to get there. You'll need a car or bus to get to Tarifa before hopping on the boat.

Thank you for your wonderful insights. I am now able to proceed with my plans. David.