you bring a very interesting point about the new Stadium in Valencia!

is the Spanish federation ready to bid for the world cup in 2018?
probably yes! Spain will try to host the World Cup in 2018:
right now they dont want to host Euro cup, they think it's a small event and probably they only want to host the World Cup.
(last Euro cup in Spain was in 1964 and Spain has not try to host the event again, last WC was in 1982).
one very big reason to try to host the WC, new stadiums, the list is impressive, almost all the big clubs:
Barça is going to renovate the Camp Nou, more capacity.
Valencia new stadium, New Mestalla.
Atletico Madrid will leave Manzanares Stadium and will play in what could be the Olympic Stadium in Madrid: La Peineta Stadium
Español also new stadium!
Sevilla will also renovate the stadium at Nervion.
Zaragoza also new stadium, New Romareda stadium
Real Sociedad stadium will also be renovated, New Anoeta
and finally the most incredible -and for me sad-:
The Cathedral, San Mames Stadium will be demolished, Athletic Bilbao also new stadium!!
So, -all time table- all the top 10 big clubs in Spain will play in new state of the art stadiums very soon, 8 clubs from the top 10!!!
Only Real Madrid has no plans for Chamartin, it was renovated in the 90's.
Betis (10th) renovated the stadium at Heliopolis in the past seasons and Deportivo did the same with Riazor.
Malaga, 2nd biggest city in Andalucia, in 2006 Rosaleda stadium was inaugurated after its rebuilding. great stadium!!
and also Las Palmas in Canary Islands built a great new stadium in 2003, Estadio Gran Canaria.
there's also talk about renovating Mallorca Stadium at Son Moix and Murcia has a great new stadium, New Condomina.
A wonderful chance for Spain to host in 2018 the World Cup!!!
(perhaps with a joint bid with our brothers from Portugal, all their big stadiums were renovated for Euro 2004)