As you may have different style of living rooms, so there are no definite solution that applies to every body. You, therefore, have to choose the design of chairs and cushions to match to your living room decoration and style the most as well as function of use.

If you choose furniture that has larger size than the size of the room's space, that probably make your room look jumble and not convenient in case you want to walk within the room. On the other hand, if the size of furniture is too small, that will make the room have too much space left. There is a very simple way on how to know the size of furniture that fit to the room. When you are buying furniture, measure the size of the furniture from edge to edge, then re-calculate the size f furniture to correspond to the scale of the room plan. Then you will have to furniture size that you can estimate on how and where to put them in the room. The other benefit of doing this way is you can imitate and arrange layout of furniture with the room as many time as you can until you satisfy.
However, please be aware that the function of use of furniture is also important, for example, if you want to put a cushion in the room, does not forget to spare little space for stretching knees and legs too.

Using 2-seats sofa would be more convenient than using 2 chairs because it will use less space as well as more convenient for 2 people to sit and talk and 3-seat sofa may inappropriate for sitting talks apart from if you intend to use it for temporary sleep or resting.

In some case that you provide not enough chair or cushion in the living room and you have more visitors, you may add additional chair when needed and you should choose the additional chair that has the same design or same colour with the existing ones. You may also have to choose the additional chair that convenient to keep and pick easily which will helping to save the space as well.

About the height of the sofa, it is really depends on individual preferences, but you should buy the sofa that high enough to make you feel most comfortable. if possible , you should give every member in your family an opportunity to sit to make sure that the cushion/chair suite to everybody needs.

Firstly, you have to consider the main function of use in order to choose the right type of table to match to your needs. For example, if you are looking for a dining that table, it should have height about 28 inches (or about 724 a millimeter), and the height of the chairs must be correspond to the table height.

Small-sized table, generally we use single small to put beside chair or cushions, which generally used for put food/snacks and beverage. So you have to consider about the function that you are going to use it for lay an ashtray, lay a lamp etc.