We have just done for a friend:
small basket (I had some already) with Christmas tissue paper in
Christmas coffee (Taylors of Harrogate)
Christmas tea
Posh sugar (a little box with sugar shapes - I know John Lewis do these but you can buy different sugar stirrers etc. quite widely)
You could also add something like Monin syrups (bought some for DP in Sainburys the other week, about £2.50 a bottle I think).
I would say either a DIY hamper or cinema vouchers or vouchers for their favourite restaurant/place. Or something they could do together like a Christmas puzzle or a game? Several places do chocolate versions of games for Christmas.
Hamper ideas: home cinema (DVD, popcorn, sweets/bottle of wine); tea/coffee as above; themed from a country or cuisine that they enjoy, e.g. Indian so different spices, packet of posh rice, mango pulp etc.; cheese and wine evening - posh biscuits for cheese (Waitrose v good for this), bottle of wine and some nice/different cheeses.
For people who have everything I tend to stick to edible items as it reduces the clutter/chances of it going in a cupboard for 20 years.