Agree with most others, butler sink all well and good in a utility, but too low for daily washing up in. Wooden work tops would be a pain too, staining, scratches, just doesn't appeal to me.
Style-wise it depends on the rest of the house, but if you want to make it look high end, granite tops are ideal and not too expensive if you go for 2cm sort of depth. Keep it neutral, nothing too showy so there's nothing to dislike.
We found worktops, tiles and glass splashbacks a lot cheaper from separate suppliers, bought over, fridge, hood etc all from different places, while rest of kitchen was Magnet (gloss white, simple brushed steel handles).
It was more expensive than Wickes for example, it cost less to fit because cupboards were already built, like Howdens, however, if you're trying to do it relatively quickly and don't have the heart to shop around for the 'perfect' thing when you're doing it for someone else, it will cost a lot more but be much simpler to get Magnet/Howdens/whoever to do it all for you.
Plain wood or white cupboards & simple tiling with the colour added in with removable accessories.