Famara on the North Shore is a perfect side/side-on spot, nice waves, if the N-E wind is there... Still a surfers and fishers typical village, while South coast is full of Hotels for Germans, buildings,...
Forget the South Windsurf Spots (las Cucharas , los Charcos...). Lots of people, rocks, very narrow beaches, gusts on start... In the southern part of the island, some sand beaches (Playa del Carmen, Playa Honda (near airport however)) can do the stuff when Famara is out.
Gone there in January so it may be totally different in Summer...
some pics here at
http://norad.homedns.org/alex/ Lanzarote albums.
some additional info on flysurf.com too.