In terms of placing the rug you have a lot of options but the most preferred way is to place the rug partially under the bed.
Rug placement under double bed.
With this placement start your rug at the middle of your bed and make sure that it runs far enough beyond your bed that you have room for foot placement while sitting on your ottoman or bench.
Make sure the rug extends the bed by at least 1 foot typical rug size for a king bed is 9x12.
Make sure that the rug itself doesn t slide.
Place the rug perpendicular under the bed with enough of the rug reaching out on the sides and in front to place your feet comfortably when getting out of bed or sitting at the foot.
In cases where you have a bench or ottoman at the foot of your bed you may want your area rug to go a few feet beyond the foot of your bed.
A full size bed or double bed measures 54 inches wide by 75 inches long.
Start rug in the middle of the bed.
If the desk slides you can put a thin rug under it.
Ideally the rug should be large enough to extend beyond the sides of the bed at least 12 inches for a twin or double bed and at least 18 inches for a queen or king.
You can go bigger but these numbers should be the minimums you want to look for.
A 6 foot by 9 foot area rug fits the bed a nightstand and a bench at the foot of the bed.
For an area rug to look balanced under a bed it should be large enough to extend beyond the sides of the bed at least 18 inches for a king or queen bed and at least 12 inches for a full or twin bed.
The general rule for placement of rugs under beds is that a rug should extend 12 to 18 inches from the sides and foot of the bed 12 inches for a twin or full bed and 18 inches for a queen or king bed.
8 x 10 or 9 x 12 king size bed remember the bigger is better rule when it comes to arranging an area rug under a king size bed.
A rug that is too small will detract from grand look and dimensions of the entire room.
A 4 foot by 6 foot or a 5 foot by 8 foot area rug fits the bottom two thirds of the bed only.
Leave at least 8 of space from the nightstands to the beginning of the rug.
As far as the under bed rug i like pelts either natural or faux instead of a rug that goes all the way under the bed.
For this you can use a padding for rugs and even special grips that they sell for the padding.
Typical rug size for a queen bed is 8x10.
Depending upon the size of the room there can be more rug extension around the bed as seen in this room by lauren nelson design but not less which would make the rug look insignificant being covered mostly by the bed.
Make sure the rug has at least 8 of space on the sides of the bed.
Do cover high traffic areas.