There are no hard and fast rules to choosing an area for your home. Ultimately it comes down to individual lifestyle, taste and budget. There are a few guidelines that would help with the decision making process.
For larger rooms and open plan spaces rugs are a great way to create defined zones and provide a warm, welcoming feet. Opt for large sized rugs and position sofas, single chairs and occasional furniture completely withing the rug zone or with some pieces just on the edges.
If the space is tight and some furniture is perhaps up against a wall, try to accommodate a rug large enough to fit under at least the front legs of sofas or chairs, but if this is not possible, having all legs of an accent chair or coffee table on the rug will also bring the look together.