What space do you need versus what you actually use. Right now we are in an odd situation. We have 1 more bedroom and a basement we actually don't need or really use that much. We also have really one more eating area than we actually NEED although we use our dining area quite often. So after 3 years of playing with the rooms I have come up with a couple of organizational ideas for those looking to use the space wisely.
First and foremost you don't have to cram every room with stuff. My extra room upstairs has a full size bed and two book shelves with two lamps. On the shelves I keep my kids books for nightly reading. I have three pictures on the wall.Other than that the room stays empty. I have in the past put our luggage under the bed but currently i have our leaf for the breakfast room table under it to keep it from getting scratches.
I use the closet to house the next phase of my kids clothes hung and ready to go. So on the left I have 2T clothes for my son, he is currently in 18 month clothes, and on the right I have size 7 for my daughter as she is in a size 6 right now. This allows for me to know what I have for the next phase of clothes and not purchase to much and be reasonable in what I pay instead of rush out for clothes when they outgrow what they are in currently. I try to keep the floor sparse, the closet is long, at least 10 feet, so i have a small cradle my father in law made in one end and the vacuum in the other with a baby gate just in case I need it in the middle. On the top shelf I have a small fan and heater and extra sheets. I do my best not to use this space for the "i don't know where to put this stuff", although i do use it as a transition space, so if we are going on vacation or doing a large project i use this room to spread out in and its wonderful.
This space for us works. Its SIMPLE to clean and keep clean. My kids can get in and out without getting caught up in playing or leaving stuff in there. Its a nice room for quests to spread out in and we are not tempted to fill it with stuff we don't need. It will show nice should we ever want to move and the furniture is so minimal its super easy to pack up and move. I encourage you to think before you start filling a room about its purpose. Is its purpose to take on the extra stuff or to be part of your home that is lovely. Total I spent around $500 for every bit of furniture/bedding/shelving/pictures. Guests love the space and ability to relax within it.
Basements, oh my lets open that can of worms, shall we. I have seen so many different uses for basements. Ours has been storage, living quarters, project room, poker room, bounce house space and overnight guest space for 6. Basements were never meant to keep your trash you never throw out, storage yes but not a place for your "i will get through that later" stuff.
Whatever you choose to use it for stay with that theme. I caution using it for storage to watch what you throw down there. Growing up my home had 4 attics, I never realized we were keeping so much trash till we had to move it all. I love the idea of having a well organized storage place. We all have Christmas decorations and camping supplies and tools we use once a year and the list goes on but keep restrictions on yourself. Just because you have the space does not mean it has to be full. I have shelves that i am not allowed to "grow" out of. This keeps the clutter down and the junk out of our storage stuff.
We loved it when we moved in because i used it as staging for unpacking, separating boxes into rooms and tackling them one stack at a time without them being in my face every moment of the day. Now we use it as a minimally decorated living quarters for quests and an extra play space for those snowy days the kids just cant get out of the house.
As far as my organization goes for this space I have a couple rules for myself. #1 I can not use any part of it for storage (it has a large closet, full bath and kitchen all with storage I could fill).#2 I must clean it like I clean the rest of the house at lease every other week. #3 I go down there with my kids once a week to use the space as a play area just to check in and make sure everything is working properly. This sounds like funny rules but no matter how often or little we use the space it needs to be kept well and updated so I try to keep it nice.
My personal use of the basement is based on working out. We have a nice wall mounted TV and elliptical down there. I love it to get away for 30 minutes. The only other pieces of furniture are a Desk (and office chair) and trundle bed for quests. In the closet I put in adjustable shelves and enough space to hang clothes a folding table and chairs an iron and ironing board and an ipod docking station all for quests to use as needed. In the kitchen just this year I got rid of my dads old dishes (to many sad memories) and opted to get a fun set of plastic dishes from target for summer dinners. I figure this can go with me anywhere and isn't to hard to pack up. I also have basic cooking utensils a pan and pot and cookie sheet in the kitchen. The bathroom I keep a ton of towels and extra emergency supplies for guests.
The bed is a little tricky. We can fit 6 sleepers at our house so I wanted to make it easy to sleep more than just 2 on a trundle, I ended up getting a trundle that had wood slats as a base instead of the older spring models. I then purchased ikea foam mattresses that are about half the height of a normal mattress and bought 2 to make it normal height. This allowes for us to take one off and place on the floor for large numbers of guests. So total we can sleep 4 without having to take up the space of 4 beds while not in use, its perfect. We can even use it for nights we have high wind (we live on top of a very high hill). We all get a bed and can sleep really well and comfortably. I would and have considered also the idea of a loft bed with a small desk or not having a bed at all and using it as a media suite with, if I went with the media suite I would rid the room of all the guest stuff as we would no longer offer it as a place to stay.
We are blessed to have this space and I want to keep it well but easy to maintain. Extra space is so easy to fill. Once again I encourage you to not use this space as "left over" truly use it for what you need or have it "show ready" (ready to be put on the market at any time) being show ready always makes you proud and want to take a nice long deep breath when you walk in.