At the start there is a nice open place with roof to skate, try new tricks, hang with other skaters from Valencia. And some skaters meet there to go on a skate by the sea.
You can also explore F1 track. And see some abandoned American Cup buildings.
There is a lot of sand on the beach, so take care of your bearings. And on the pavement surface is designed to prevent inline skating and using scooters. And they did very good job with that.
So if you want some speed, bus lane is your only option.
http://www.strava.com/routes/4368551