if you want to scuba dive go here... it is by far the best diving centre in lanzarote
+ its one of the only licensed dive centres on the island. most of them are operating illegally. plus they have oxegen available / boats etc.
its right on the playa chica beach between farionnes hotel and old town. with lovely little sheltered cove. best diving is on the reef out here.
i go there every january and to be honest its mainly for relax / scuba so i cant comment on the excursions.. did the catamaran one year was pretty good.
was over in april and there is a lot of places closed down / boarded up compared to previous years.....
bodenca's is a really nice polish restaurant just above the old town (also my favourite place to eat albiet a little more expensive).
rory gallagher from the revs plays over there most nights, used to be in buddys bar in old town but he has now moved to another bar further up the strip.. very good live music and athmosphere
if you like surfing you need to head across the island to caleta del farmara and hit up
these guys are also brilliant. full day with lessons and rental and lunch is around 50euros. they will usually pick you up from your hotel and bring you across.
hope this helps.