There are lots of places, the costa brava can be as lively or as laid back as you wish, i would say Lloret and Calella are definately the more livelier , Tossa and Blanes are the more laid back , Santa Susanna is also a very nice resort close enough to Malgrat which has a lot more english style bars, Pineda is rather quiet not too loud, but again close enough to calella if you want nightclubs , Fenals is quite busy and the next resort from Lloret so again you have the choice of . A lot depends on what you want from your holiday .

i would look at malgrat rather than tossa. it has shops/bars/restaurants and is flat!
santa sussanah would also be an option but i would want to be nearer the malgrat end than the station end. almost all the s/susannah hotels have some sort of evening entertainment.
lloret and calella are the liveliest resorts by far, but i think tossa may be too quiet.
make sure you read all the hotel reviews before booking to ensure as few as possible suprises.