The Grandvrio is like several other beachfront hotels on Saipan - in need of refurbishment. The lobby and pool areas look fun and inviting, but the rooms are basic, small and poorly fitted out. The standard room I was given had two single beds, quite uncomfortable. Pillows were equally hard and unpleasant. I asked for a large bed when I booked and an airport pickup. Neither were delivered. I'm guessing that the hotel does not read the special requests on the bookings.
The room is dark too, only a few lights and, a pet hate of mine, hardly any accessible power outlets. The bathroom was falling to bits, the shower over the bath tub was not very good and most of the TV channels were "subject to negotiation" between the hotel and the cable service, i.e. not available.
On the upside, the staff were mostly friendly and helpful. And the location is pretty good too, because you can walk easily to the main area of Garapan. If you can book a room at the Hyatt, do it.