Mine was the Twilight Grey and had the tan leather... I presume by "tan" people mean the Alezan orange. Its worth noting that this was an optional extra ontop of the GT pack, costing £600 more over the normal leather.
They are very much down to an individuals taste. I think they look nice with the grey, but on the blue or ginger cars they would look terrible.
Its also worth noting they are very hard to photograph! In photos of my interior they looked really bright orange! But in reality they are more beige.
As with any leather you need to really look after them. I cleaned and treated mine every 3 months and they looked brand new still. The only bit on the Alezan orange interiors which really deteriates quick is the gear knob. Mine looked really disgusting when i bought the car and it had only done 20k miles. I replaced it with a genuine one which isnt cheap at all. But you can always go for an aftermarket black or carbon one to save a lot of money!
Take a look at the Alezan gear knob I refurbished for Mac last year:)