Cant comment about the Old Town Hilton, but the Hilton Prague has a very good lounge (breakfast pancake was really yummy) and the rooms are fairly nice. Location is not as bad as I had expected, its only a 10-15min walk to the Old Town Square, and there is a subway station (Florenc) behind the hotel if you need to use it. I have dropped to Gold but was treated very well there (on an award stay).