The new all business class service from New York to London. On their website, I noticed that the cabin has been configured so that each passenger has 21 sq. feet of space – so you are essentially doing a timeshare of 21 sq. feet for five hours for $2500 (introductory rate), or $119 per sq.foot.

By comparison, a city view Tower room at the Four Seasons in NYC is $500/night for a 500 sq. ft room – so 100 bucks per sq. foot but for 24 hours.
Photo from http://www.eosairlines.com/