Depends on them as individuals.
I always make sure and get the ones that enjoy to have a drink a bottle of their favorite liquor. I also ensure that the lady of the house is always included with food stuffs such as chocolates, homemade jellies, jams, pickles, coffee, etc.
Some of the people who grant me access are not drinkers therefore they get very much the same minus the liquor and maybe a ham or something extra food wise included. The homemade stuff is always a hit, it shows planning, work and thought maybe a bit moreso than pulling out a wallet.