Hi
Haven't stayed at the Hilton, but have stayed at the Sofitel three times (most recently on 3rd October) and really liked it.
How many weeks are you away? If you are away for two weeks, then the hotel/parking packages are good. If you are away longer, then try pricing the hotel and parking seperately (through holidayextras.com). We went for 18 nights and it worked out cheaper to book seperately than to book the package and pay for the extra nights parking...
Boo