We're scheduled to land at LHR T3 at about 10pm on a weekday and would leave by 10am to rent a car from Avis

1) Is the Skyline's estimates that a taxi costs £10 generally accurate?
http://www.starwoodhotels.com/sherat...propertyID=268

If so, seems easier than the Hoppa for two and faster than going from T3 to the Central bus station to get a 105/111/140/285.

2) Any reason to prefer the Marriott or anything else in the immediate area?