Had a one-night stay here prior to catching a morning flight out of CDG. As Gold, I was upgraded to the executive floor and given lounge access. As people have mentioned, the lounge is on the first floor next to the restaurant-- it wasn't particularly nice (though not at all crowded); I would much rather have had the crowds and the view from the top floor. After having spent the week at a hotel in the city, I have to say that the Hilton CDG felt somewhat soul-less. It was just a bit too large and bland for my liking (and I've stayed in a reasonable number of Hiltons over the past few years). Still, it worked quite well to give me easy access to the airport in the morning, without having to worry about traffic.
I was told that there was no option for a bus from the hotel to T1, only the CDGval train. Fortunately, I found that connection quite easy, as I only had one suitcase to haul about.