We really enjoyed our stay at Maria's lovely apartment. We are a family of 6 with 4 tweenagers, but the place swallowed us up - we were pleasantly surprised to find 2 full size double beds in one of the bedrooms, so it accommodated us comfortably.
The apartment is super easy to find, and about a 10/15 min walk from the old town. The terrace is lovely for breakfast.
Maria left a very helpful info pack. Our highlight was cycling from the apartment to the port/beach on very safe cycle lanes and cycle parks.
Valencia is a very chilled city, and a great place to visit with kids.