Step 1. Look unfriendly. No matter what was said to give those people the impression that their presence is desirable (like repeated phone calls explaining how there's plenty of room, it makes the most sense, you'll be able to spend more time with them, etc), when they arrive keep a frown on your face, and, if possible, add a little wrinkling between the eyebrows. Nothing says "Go away!" like a screwed up face.
Step 2. Don't make them feel "at home" with bizarre statements like "welcome", "It's good to see you", "I'll show you around" or even "here are some towels for you to use". Under NO CIRCUMSTANCE do you want your foul smelling impositions to think that they can treat your house like a home.
Step 3. DO NOT interrupt your regular plans. Sure, the visitors may have driven thousands of miles to see you, but that doesn't mean you want to see THEM. Stick to your Friday dinner plans with the friends you see twice a week. For Pete's sake, you haven't seen them for FOUR WHOLE DAYS, which means you have LOTS of catching up to do -- which also justifies not including the guests in your conversation. At all.
Step 4. Ask your guests to stay quietly in their rooms as long as possible in the morning "for the sake of the children". That way they won't bother you, even if you're up early. Remember: you only reluctantly conceded to having them stay, not to be your friends.
Step 5. Make it clear that you are NOT a doormat, and you will not be providing meals for your guests. Of course you'll make the usual four separate, individual breakfasts for your family, but the freeloaders can darn well forage for themselves. After all, there ARE leftovers in the fridge. Hopefully, they'll even clear out the end-of-date food you are too sensible to eat. If you prefer, you can always go out to eat. If you do it right, you can sit at opposite ends of the table and not have to talk to them at all.
Step 6. Make lots of plans that the interlopers can't participate in. if that doesn't work, make plans with them, but don't bother showing up when you say you will, and be sure to leave without telling them. If you do have to do something together, make sure it's loud and unpleasant, and mislead them as to what their expectations should be. If you (unfortunately) have to do two activities together, be sure to invite your true friends to "unexpectedly" show up, so you can, again, ignore these other people.
Step 7. Practice your veiled insults before they arrive, so you can use priceless lines like "I love my children too much to do that" when the guests kiss their kids goodnight and send them to PUT THEMSELVES TO BED. Bad parenting must ALWAYS be commented on.
Finally, Step 8. No mingling. Remember, fraternization leads to contamination, so make sure to find ways to keep any children from actually interacting (reference Step 4). For your part, do not participate in small talk, like asking about your guests' trip, or inquiring about them as individuals. Such activities may lead to a false sense of friendship, at least on their part.
Follow these tips and you should have your visitors crying to themselves in the shower within two days. Keep up the good work! With effort, you may even encourage them to move on a day earlier than planned. If you succeed, bravo! If not, well, it's not like you're ever going to visit THEM, is it?