Hello Pussycat,
We have been living in the Costs Brava for 7-8 years now, all around L'Estartit area and Tamariu and we used to have two terriers, a Scottish Terrier and a West Highland White one and a Ginger Tom cat. They used to go with us where ever we went and we have never had any problems whatsoever. The only thing is that restaurants are a little reluctant to let them in. However, if you are a regular, even that is not a problem.
We, at one time, were weighing up and deciding like you are now, where to go ? south or north, and we chose North for the following reasons: We love to travel by camper, so we thought North was more central, close to France, Italy the rest of Spain etc. Girona is a fabulous flying hub and excellent to get to and from, even with public transport. Even Barcelona is not far away for long haul flights. The temperature suited us better because it is not quite so hot in the summer and warm enough in the winter.(We were sitting out all day on jan 1 last) Also we like the green nature around here, it is not quite so yellow and dusty as down south.
The Costa Brava area is very cosmopolitan many nationalities live here all year round and activities take place on a regular basis. In fact if you were so enclined, you can be occupied with one thing or another very day. (Not that we are). Organisation like Conservatives abroad, English expats and U3A are all very active and many more. Golf, tennis librabry etc. you name it you can find it here.
We also feel that the Costa Brava has lost less of it's original Spanish traditional character. Many places do not have high rise (except playa d'aro). And there are still lots of lovely little coves and hidden beaches to explore, especially out of season (July August) The people are exceedingly friendly and can not do enough to try and help. So to sum it up. We would chose Costa Brava all over again.
If you want more info just ask. Hope this helps for now