If the Hilton is the hotel RSSC uses, we stayed there last year and ate at their roof top restaurant, and it was nice...pretty view of the Acropolis at night. But then there are those great restaurants and all the activity in the Plaka! Taxi's were on strike when we were there, so that made our decision for us.

I agree about not needing a guide. Just get cabs to the various sights. We only hired a driver (through greecetravel.com because we wanted to go out to the Sounian (sp?) Coast for the scenery and to have a late lunch. He just waited for us at the Acropolis, and did a drive by of other sites.