My "best" ground delay was last summer at LGW. Flying CO BizFirst LGW-EWR with my wife after a week in London (without the kids) for our 10th anniversary. Got to LGW at 1pm for the 3pm return flight, only to be handed a letter apologising for a delay of unknown duration due to mechanical difficulties; more info would follow at 2:30pm.

Went to the Pres. Club, where they announced that a buffet lunch would be served at 2pm - just in time for the first match of the World Cup starting that day (Scotland-Brazil)!! Watching the World Cup in London was certainly the way to do it - even if 60% of the crowd were from USA.

They kept extending the delay, until 6pm, when they announced that the engine needed replacement, and we would not leave until 11pm - after the morning flight from EWR arrived and was turned around. Then, they gave each person 25 Pound vouchers for any food shoppe in LGW - we spent 20 total on dinner, and the remaining 30 buying candy for family & friends at a store that honored the vouchers.

CO topped it off with our choice of 20,000 OP miles or $800 voucher per person.