We (we and our 2 kids) spent our holidays in this beautiful apartment in front of the sea: the view is really amazing! The apartment was really clean, with towels and bed sheet available and the kitchen is well equipped. The house is in a very calm zone in Malvarosa and easy to reach by bus (19-31-32). Markets and all you need are very close to home (about 5 m walk). Ines helped us with everything, taking the first day a map of the city and some tourist guides (in Italian). She gave information on transport (it is very appropriate to take bonobus, a rechargeable travel card: kids pay over 7 y.o.), on restaurants,... she is very kind and always available by phone.
I think that Valencia is a very good destination for family vacation. Kids were enthusiastic for Science Museum, Gulliver park, Biopark... there are a lot of great experiences you can have! And if the house is confortable (as we had), you have a top vacation.