My partner and I stayed at the Westin Valencia two weeks ago. I've no status with Starwood, so no upgrades from the 'standard' room that we'd booked, however it was anything but standard. We were very impressed, the room was enormous, the marble bathroom was huge, with a full walk in shower for two, a full bath, separate toilet, sitting area and one of the largest and most comfortable beds I've ever slept in.
The hotel is quite lovely, really tastefully decorated, more of a classic contemporary feel, but sparklingly clean and beautifully presented. Location of the hotel, as posted previously, is great. A short walk into the old town, but neatly tucked into a quiet neighbourhood.
Staff were good too. Efficient and professional, without any fuss. We didn't eat at the hotel, so I can't comment on the restaurants, but I'd certainly recommend this property. I can't compare it to any other properties in Valencia, however I'd not hesitate to return to the Westin.