It is the only reason all my friends are Amish.
That, and they like to help around the house and never ask me computer questions.
Just pick up. Gather the glasses and dishes and wash them. When you finish (if they haven’t left), don’t sit. Stay on your feet. Even the freshest guests will get the hint.
I second, “Well, it was absolutely lovely to see you! We have to do this again sometime.”
Release the hounds.
Disclaimer: My dad never actually used this to get rid of someone–it was only ever said as the guests were already making plans to leave, and it usually got a good laugh.
He’d yawn and stretch and say to Mom, “Honey, let’s go to bed so these nice people can go home!”
This made me laugh and laugh.
To the point of the OP, one thing I’ll do is just start doing whatever it is I need to do … most of the people who are likely to be our guests are people to whom I’d feel comfortable enough to say “hey, you’re free to check out the TV or grab a snack – I’ve got to get started on cleaning out this closet – the Mob called and they want Jimmy Hoffa back.” Even though they are genuinely welcome to watch TV or have a snack, a lot of people will take that opportunity to leave. My best friend will come help me clean the closet, also a good thing. My mom will start helping with the closet, and then tell me I’m doing it wrong and take over the project – I have really perfected this strategy with her over the years. 
I tend to speak rather bluntly, but my wife told me to tone it down a bit when I told some guests, “Get out of my house.”
We’ve got a couple of friends who simply will not take a hint. So for them, we just start doing whatever we need to do - clean the house, chores, whatever. Or even leave the house to run an errand (which generally requires that they leave as well.) What stinks is if you don’t really have any chores to do. Maybe you just want to read, watch TV, or nap - but just want them to leave. Its kinda sad when a friend is so lonely/bored that they have nothing better to do than watch you do chores.
Many/most of our friends and family know that we tend to go to sleep early, so we pretty blatantly just say we are tired - or my wife will just fall asleep on the couch.
What I really hate is when people start to leave - get their coats on and head towards the door - and then stand there and gab on and on, starting new conversations and such. I have little tolerance for that, and will say “Either leave or take your coat off and sit back down.” But like I said up front, I tend to speak my mind bluntly…
Feign death until, embarrassed by the awkward silence, they leave of their own accord.
(OK, that was a Far Side cartoon). I can’t remember the last time I had to kick someone out, but I’d probably go for something like “I hope this doesn’t seem rude, but I’m going to have to [insert genuine reason] in a little while, but it’s been great seeing you… etc.”
When you are making plans with the folks who like to linger, you should give then an end time. “Sure, noon sounds great, and we can visit until about 2, at which point we have to <go visit my aunt, take the kids to ballet class, whatever>” Then, at the decided-upon time, get up and say, “Well this has been lovely, but as I mentioned, we have to <go visit my aunt, take the kids to ballet class, whatever>”
I think it is more polite when it has been mentioned before and isn’t coming out of the blue.
I believe Miss Manners tells of a man who would look dramatically at his wrist and say “You naughty watch, for driving my guests away!”
Me, I just say “I’m sorry, but I really need to <whatever> now,” and whatever may well include sleeping or being alone. But then, I only have very close friends or family as visitors, and they all know that I have limited tolerance for company and don’t take it personally.
You just have to lay it out up front. “Sure! Stop by for a little bit. We have a thing at 4:00, but we can chat for a couple hours before we have to get ready.”
I take a preventive approach to this problem by being so coarse, caustic, and consistently disagreeable that nobody would ever consent to be a guest in my house in the first place.
Release the robotic Richard Simmons.
My FIL just says “Make yourselves at home”, gets up and goes to bed. Of course that leaves us stuck there with the guests, half the times.
I never kick people out. Generally I don’t get annoyed with people being over unless they’re annoying people, in which case they don’t get invited (or at least not twice).
If I really have something to do, I just won’t invite anyone until I’m done. If people invite themselves and I don’t feel like company, I don’t answer the door. I won’t invite anyone over if I think I might want to sleep or read or whatever anytime soon. I make sure my schedule is clear, I’m in the mood to hang out, and they’re people I want to hang out with. I enjoy the company of my friends and when I invite them over, they can stay as long as they want. If I get tired I’ll stand up and be like “alright, man, you wore me out, I’m goin’ to bed, there’s a pillow & blanket in the closet if ya wanna stay”, shake hands, and that’s that. Most of the time they leave, sometimes they stay. I don’t care either way.
I guess I really don’t understand why people get so irritable about people being in their house. If you don’t like being around them so much or you’ve got stuff to do, why did you invite them? If you do like being around them and you don’t have stuff to do, what do you care if they stay? If you just don’t like company, meet people elsewhere so you can leave when you start feeling crabby, instead of making your guests feel they’ve done something wrong.
Not exactly on point, but I have to share this story.
Last year my grandmother fell and broke her arm while vacuuming her condo. She needed to have surgery to repair the break, and the surgeon said that she would need constant care for two weeks. Grandma ended up moving in with my parents for that time.
I’ve mentioned before that my older sister is autistic. She lives with our parents and hates when anyone disrupts her routines. So it was torture for her when Grandma-the-control-freak was there – especially since Grandma has taken to criticizing my sister when she thinks no one is listening. For two weeks, all my sister heard was: “Nancy, be quiet.” “Nancy, what are you doing?” “Nancy, get out of there.” Etc., etc, etc.
So Nancy (bless her!) decided to remind Grandma that she was still just a guest in our parents’ house. One morning toward the end of Grandma’s recovery, Nancy stood in front of Grandma at the kitchen table, held up four fingers, glared at Grandma and walked away. The next day was three fingers, each one representing the number of days until Grandma left. Dad said he almost exploded from trying not to laugh.
If it’s late at night, my husband starts brushing his teeth. Most people get the hint.
“Well, dear, I guess we really ought to go to bed - these folks look as if they’d like to go home.”
I’m introverted. I like socializing, but in small doses. Keeping up conversations, laughing at all the right times, being polite, etc. drains my energy (although I’ve gotten better adjusting as I’ve gotten older). So long visits inevitably do a number on me.
Also, I do well with routine, not so well with unpredictability. I don’t entertain much (very very infrequently), so already having a guest is a disruption in itself. And then when the visit goes on longer than I anticipated, I feel unprepared socially, like my script has run out of pages. Yes, I know I’m weird.
My brother, my friend and I dropped by to see Grandfather one evening. He remarked as we walked in “I was just having some soup” and pushed the bowl off to one side.
After a while (and mid-conversation) Grandfather said “My soup’s getting cold. You’d better go now” and pulled his bowl back. He then said to my friend “It was nice to see you again love. Drop in next time you’re down - but don’t stay too long”. He then waved us out the door.
You always knew where you stood with Grandfather 