Some fairly major changes here. Revised to include separate sections for solo, couple, and group living, and get away from the previous focus on group living. Actually, most of this is excepted from an early draft of The Polyamorous Home. Updated 11/25/16
On the surface, this is more for the polycules who live together. However, solo polyam folk and couples who live together and have other partners who visit also sometimes need to worry about who sleeps where. Michael and I live as a couple. Almost every time one of my metamours visits they ask if I mind them sleeping with Michael and insist they’ll be ok on the couch. (Usually, I end up taking the couch.) We’ve tried all of us sleeping together with some metamours, but we don’t have a big enough bed (especially for when I was pregnant!). So, yeah, unless you never sleep over, chances are you’ll need to work out sleeping arrangements.
Here are the pros and cons of a few possible sleeping arrangements for polyamorous relationships. If you have experience with possibilities that I miss or some pros and cons of your own you’d like to add, please leave a comment.

Solo Living
One Bedroom Shared with Guests
If you and your partners are comfortable with it, you can have one bed that visiting partners share with you. Depending on your comfort levels and needs for personal space, you can have partners spend the night. Alternatively, you can use the bed for cuddles and/or sex with your partners going home at the end of the night.
Having just one bedroom is cheaper than paying for a home with two bedrooms, but may not be comfortable for everyone.
One bedroom, with a couch or blow up mattress
You might be comfortable sharing your bed for sex and/or cuddles, but want space when you sleep. Or you might prefer not to share your bed at all. You have options for a partner spending the night, even if your home only has one bedroom. Your partners can sleep on a pullout couch, blow up mattress, or other temporary sleep spot.
Guest Bedroom
If you can afford it, a second bedroom is another option. You might use your bed for cuddles and/or sex. At night, your partners can sleep in the guest room. Or your bedroom might be just for you and physical intimacy stays in the guest room.
Having a second bedroom is more expensive, which means it won’t work for everyone.
Couple Living
Shared bed and bedroom with family
Unless there are laws against it (and some places there are) you and any other family members (kids, your sister-in-law, your mother…) who live with you can share a bedroom, even the same bed. The general reaction from my US readers is going to be “OMG, what!” However, it was pretty common in Europe and the US a few hundred years ago. It is still normal in some parts of the world. Partly because not everyone can afford separate bedrooms (or beds) for everyone, partly because it is easier to keep warm in the winter when you were sharing body heat. The modern Western obsession with privacy is just that—modern and Western.
Shared bed and bedroom
The couple to share a bed and bedroom. Other family members (if any) have their own room(s). This is the default in most parts of the US
Shared bedroom, separate beds
Why not? It isn’t common, and it sounds like something out of “I Love Lucy,” but the for some couples separate beds just make sense. No one can steal the covers and a restless sleeper isn’t keeping their partner awake. Maybe someone has medical equipment they need to sleep with. Separate beds aren’t as physically intimate as a shared bed, but you can still fall asleep listening to each other breathe. Bonus: having a visiting polyam partner spend the night in your bed won’t mean kicking your partner out of their bed.
Separate bedrooms
Not an option for everyone if only because of the increased the cost. However, some couples have found it suits them to keep separate bedrooms and only sleep together occasionally. This is actually increasingly common among some monogamous couples. Polyam folk who advocate for this arrangement say your sleep is healthier and less disrupted, and the times you cherished the times you sleep together because they are intentional.
Group Living
Individual Bedrooms
Just what it says—everyone has their own bedroom.
Pros: No worries about how to rearrange things if a metamour comes over. Privacy. Extra space. Flexibility.
Cons: Increased cost of living. Less communal space. For large group marriages, it will be hard to find a place with enough bedrooms.
Master Bedroom
Every adult in the family shares one bedroom and (possibly) one bed. With standard-sized bedrooms in the US, this can work comfortably for a triad and be a squeeze for a quad. I’ve seen bedrooms (and beds) that would fit larger groups comfortably, but that aren’t easy to find or in most peoples’ budgets.
Pros: Shared bedroom=relationship bonding. Lower cost of living than other options.
Cons: Lack of closet/dresser space, crowded bed, NO privacy, lots of people on the couch/floor/recliner if a non-resident poly partner comes over.
Master Bedroom and Guest Bedroom
Of course, if you have more than one bedroom in your home, you can always make one the master bedroom and one the guest room. This way, there is a place for people to go if they need a night on their own once in a while. As well as a place for non-resident polyam partners and resident polyam partners to hook up without displacing the rest of the family.
Pros: No worries about how to rearrange things if a metamour comes over. Extra storage/closet space.
Cons: Increased cost of living.
Couple Bedrooms
Whether or not your family group is made up of distinct couples, you can set up your bedrooms to be shared by two people in your family. In the US, most bedrooms are built with the expectation that one or two people will use them. So this works better space-wise that everyone sharing one room. It’s also less expensive than getting a place big enough for everyone to have their own room.
Pros: Enough closet/dresser space for everyone. Reasonable cost of living. Some privacy. Only one person on the couch if a non-resident polyam partner comes over.
Cons: Need to rearrange everyone if want to swap partners for a night. Possible jealousies or perception of favorites. Lack of flexibility.
Two Bedrooms, “Hinge” Moving Back and Forth
This arrangement is difficult to make work. It takes a lot of communication and one or more family members who are comfortable not having their “own” bedroom space.
Pros: Plenty of room. Some privacy. Flexibility. Less likely someone needs to find a couch if a non-resident poly partner spends the night.
Cons: Higher cost of living then sharing a room. Possibility of jealousy/tension/perception of favorites.
Sleeping Bedroom and Stuff Bedroom
This idea comes from my friend Lauren. When she first suggested I didn’t know anyone who had tried it. Since then I’ve heard from a few people who say it has worked really well for their polycule.
Two bedrooms — one is a pure sleeping room, with king size bed, piles of futons on the floor, whatever sleeping set up you need to fit everyone comfortably. And nothing in it but the bed. In the other put everyone’s dressers, most of the hanging clothes, and any other furniture you’d normally put in a bedroom. If you have a third bedroom, set it up as an office, with everyone’s computer/desk setup.
Pros: Lots of cuddle time, room enough for everyone (at least up to 4 or 5 spice, anyway), reasonable cost of living.
Cons: No privacy, there might not be a big enough (and affordable) bed.
Mix and Match
Maybe one member of your family just needs to sleep alone for whatever reason, but everyone else is cuddle bugs. Well, that one person can have their own room while the rest of you have a big shared room. Maybe you like the idea of Sleeping and Stuff bedrooms, but also want a guest room for when people visit. Pick and choose what works for you a la carte as it were.
There are other options out there, but this covers the basic sleeping arrangements for polyam folk.