We stayed at the Hilton Hua Hin (had originally booked Cha Am but changed it when a friend said it was quite remote and they spent all their time taking taxi's into Hua Hin).
Personally I would not recommend the Hilton. They had turned off the air con in all the public areas because the hotel was only half full at the time. It was SO hot when waiting for a lift (and in it) and in the lobby. I do not approve of a 4* hotel cost cutting at the expense of the guests.
They did not change our bedding (spilt a bit of coke on the sheet and it was there for days). It should be my choice not to have the sheets changed daily not theirs.
The hotel had been quite newly refurbished, in a Japanese style so everything was sort of low slung! The sofa's in the bar were so deep that if you tried to sit back your legs stuck straight out in front of you. Only comfortable way to sit was perched on the edge of the seat or with 6 cushions behind your back.
It is in a nice location though, right on the beach with a nice pool and walking distance from the night market (through the street with the obliging young ladies in it, my husband insisted it was the only route to 'town' - still, best offers he's ever likely to get). Shops and eating places all round. I suppose I'm nit picking a bit but I just don't think it had the wow factor I've experienced at other far east hotels.
I hear the Sofitel is very good.
Stayed in Bangkok beforehand, in the Desert Orchid Sheraton - absolutely fabulous hotel. My son stayed in the Hilton there and said it was rubbish, shower didn't work properly and generally not impressed.
Have a fantastic holiday.