don't scare to echobrain
it's not centrical, but holliday inn valencia-san luis isn't so bad placed.
Yes you have to walk, but valencia is plain.
I even think that is closer to the center that i am while staying in valencia (by the side of the city of arts and science)
and it's very esasy to get to the center. Just follow ausias march, then cross an avenue (peris i valero) in an square with an strange thin, tall, pink coloured sculpturte in the center (also known as the pink panther, despite it represents a water bomb)
then follow the street just in front with the train tracks on the left and this leads you to the north station, in the center.
http://callejero.paginasamarillas.e...acio&idCalle=30253&idioma=spa&site=callejero#
But it's a bit bad located for getting to the fireworks, it's a long walk.
Don't even think about renting a car in valencia during fallas. You'll notice why you don't need it when you are there.
I never use it in fallas.
I walk a lot in fallas, the best way to see the fallas, and use metro to get from the center to nou campanar, or a taxi to get back home when i really tired and i'm far. As your hotel isn't in the center, a taxi can leave you at the door of your hotel easily.
Anyway you can still try to find something more centrical.