Only used mine for flights, saved about £5,000 so far but now have trouble finding deals in school hols unless we do Heathrow~Miami route.
My Brother uses his for upgrades all the time, he has 550,000 so plenty to go at, we only have 200,000 between 3 of us.
We changed our airmiles into Virgin gift vouchers and bought Christmas hampers with the vouchers from Spicers Hampers, they are a company that will take Virgin gift vouchers through the post. My brother used them for Virgin Wines.