This comes from our facebook group- one of our members asked for suggestions for a day trip, preferably within an hour of Valencia and that provides for a short nature walk as well and he got some great responses!
Navajas (hiking and beautiful scenery) http://www.navajas.es/portal/index.php
Peñiscola (castle) http://www.peniscola.org/ca/
Albufera http://www.albufera.com/
Chulilla (hiking paths and a cave) http://www.chulilla.es/
Xátiva (castle) http://www.xativaturismo.com
Bocairent (caves, medieval town, snow caves) http://www.bocairent.org/
Vall d'Uixo (caves of San José have an underground river with a boat ride through it) http://www.lavallduixo.es/vallduixoPublic/portada/ciudad/turismo.html
Alcalá del Jucar (about an hour and a half away, cave homes on the side of the mountain that you can visit, also the Jucar river runs through the town, hiking) http://www.alcaladeljucar.net/menu.htm
Chelva (Roman aqueduct) http://www.chelva.es/
Alcoy (hiking and parks) http://www.alcoiturisme.com/home/index.php
Morella (about two hours from Valencia) http://www.morella.net/
Vías Verdes near Segorbe http://www.viasverdes.com/
Sagunto Castle (great little restaurants and spectacular views from the castle) http://www.saguntoweb.com/castillosagunto
Altea (beautiful beach town 1 1/2 hours from Valencia)
http://www.altea.es/