Valencia is a very nice city, and Tryp Oceanic is a good starting point. Very friendly staff, clean room, good breakfast with a lot of variety (until 10:45), nice (not very big) swimming pool to cool down after a hot day.
The Ciutat de les Arts i les Ciències is closeby, 5 minutes walking. Also two shoppingcenters and enough restaurants/places to eat.
Rent a bike at 'Do you bike'. This is cheaper than most other companies, the shop is nearby the hotel. I rented a bike for a week and did all my trips by bike. The beach is 10 minutes, city center around 15. Also late at night you can easily go by bike through the park, there is enough light and still a lot of people are around, walking their dogs, jogging or just chatting.