Hi Dawn,
There is a lovely tapas bar " La Bodega" just a stone throw from you, in Plaza Domingo in Los Delfines / Calan Blanes(right next to the blue arch), for when you dont want to get the car. It's great too if you want to mix and match your food, right next door is the Mexican Cantina and you can order your food from either one and have a great varied menu.
If you are taking the car however, I would recommend Ciutadella, if you make your way right to the center of the old town (well, its all old) but if you ask anyone where the fish market is, you'll find plenty of little places that do tapas - our favorite being C'as Marino.
Right on the Ferreries round-about you'll see a bar call Vimpi, that also has a very large selection of tapas.