The first, but often over emphasized, thing to do when choosing a new rug is to measure the space that you want your rug to fill. This is obviously an important part but one that can often be focused too heavily upon. While there are some sizes that tend to fit better in certain spaces, the rule we like to live by is buy what you love.
The fact of the matter is that a good handmade rug could easily last you 30 or 40 years and you want to be sure that it is something you love and that brings you joy and happiness every time you see it. If you buy a rug mainly because it seems to work in the space, eventually, you will stop noticing it and it will just become part of the background. Oriental rugs are meant to be pieces of art that you live with so when measuring, find the minimum and maximum size that could work so as to give you more flexibility in finding the rug you love.
Dining rooms tend to be more size dependent that any other room because you must be sure that your table can fit comfortably on it and not have the chairs get caught on the edges when they are pulled out or in. Due to this, we have found that an 8' x 10' rug tends to work best with a 6 person table with room in case a leaf is put in to extend the table. Similarly for larger dining room tables, a 9' x 12' can work well. Just be sure your chairs fit on the rug when scooted out.'
Living rooms are exciting to choose a rug for because there are so many ways which a rug can be used that you have so many options. In this regard, it mostly depends on which rug you love and then positioning your rug accordingly. You can choose something as small as a 5' x 7' or a 6' x 9' and place your furniture around the rug with a table in the middle; or place the rug in front of a window or fireplace and angle your furniture at that. Furthermore, you could choose a larger rug, such as an 8' x 10' with a similar layout as the smaller rugs but place parts of the furniture on top of the rug. Again, you could go even larger with a 9' x 12' or over-sized rug and place all the furniture on top of the rug. With your living room, when in doubt, go with what you love and the layout of your furniture will follow.
-Be sure to check and vacuum under furniture periodically to avoid moth damage-
Hallways tend to be fairly straightforward and mostly determined by width. While there is more leeway on how much flooring you have showing on the ends, the sides are often more constraining, especially in particularly narrow hallways. Generally, one would not want to have the rug touching the walls and in the case of nice hardwood flooring, you may specifically want a couple inches of flooring showing. However, do not forget that the most important thing when purchasing a quality rug is finding one that you love. If it is a rug that truly brings you joy, then you will not mind it crowding the wall a bit.
Finding a rug for your bedroom is important because it is likely the first thing you will put your feet on in the morning and you want to be sure you begin your day with something you love. A simple solution is to get a large rug and place your bed on top of it. An 8' x 10' or 9' x 12' works well with a queen or king sized bed by framing the bed and leaving a couple feet on either side. Another method, if you would rather not pay for a large portion of the rug which would be covered by a bed, is to place runners on either side of the bed. This method is nice because it leaves you a lot of room to experiment and customize exactly what you would like. You can even add a smaller rug at the foot of the bed to bring it all together.
-Be sure to check and vacuum under the bed periodically to avoid moth damage-