I live in a Georgian pile which is beautiful but very difficult to heat - I don't really like visitors keeping their shoes on so we've made over the gun room into a little area full of slippers for them to just pop on, with some nice guest baskets full of little things they might appreciate while they're here - fresh towels, tampax, mooncups, a cafetiere and a tea pot, the Wifi password and passwords to all our online banking in case they run short of cash while they're over and some home made lemon drizzle cake. And some Elsa dresses for any little boys who are over, and some wellies and tutus for any highly original girls.
I don't mind said guests dropping in unannounced in the slightest - what a sad world if friends and family all felt they had to stand on ceremony! I have absolutely no problem calling down 'I'm having a shit right now, but pop the kettle on and I'll be there in a mo!'. It's especially nice if MIL comes round and throws all my things out and replaced them with cheap tat, or cooks me a meal she knows fine well I don't like, whilst I'm out. I sometimes wonder whether some MNers actually like their friends and MILs, if they have a problem with this!
If friends are still there on Christmas Eve, I will make them up a little hamper as I do for the children, as would hate anyone to feel left out. We don't go overboard on it, so just some nice bits they might appreciate like new pyjamas (White Company have some lovely ones!), a bottle of single malt, a nice new book and a DVD box set.
One thing I absolutely do insist on though is that when we go out my friendly massive dog is allowed off-leash - what a sad world if people aren't prepared to say hello to him while they're sharing their picnic with him!