Hi Bobby50
We have used the route Zaragosa Valencia Alicante a few times.
The A23 dual carriageway most of the way down from Zaragosa to Sagunt just above Valencia. The road is being updated as we talk about it and some sections are not yet complete, but overall it's a good route. From Sagunt down to Valencia and round is motorway then the route across to albacete and then pick up the A31 dual carriageway down to Alicante/Elche.
Coming down from San Sebastion to Pamplona and Zaragoza is mostly dual carriageway/motorway even keeping clear of the toll roads is not complicated
There is also a short cut which by passes Zaragosa, a route taken by a lot of lorry drivers, cuts across at La Alumnia and is a fairly straight road.
We shall continue to use this route and look forward to the A23 being completed.