Brittany doesnt have much flavor nor much of interest besides its position for colonization and decent naval capability. It's fairly common in MP due to its second or third-rate nature not threatening its neighboring powers, but I don't think its a good choice in SP. Based on your regional choice I would recommend playing a different nation.
If you want to play colonial and abandon continental politics, play England/Portugal. If you want to dominate continental europe, play France. If you want to have a fun single-player game from an initial weak position, play Provence (can go for france, stay as provence, or form jerusalem).