Seating - Stools
A simple stool for use on a slab floor. Experiment with different backings such as item frames, as well as different slabs to suit your room.
(Submitted by UltraWarrior7651)

Placing carpet on top of a stair is another creative way to create a dining stool in a modern dining room.
(Submitted by sagemcbride)

A Painting is applied to the back of simple fence and pressure plate (usually used as a table) to create a wonderful looking raise chair.
If your Stools are in a slab floor and you need a bit of extra height - this solution looks amazing - Place any slab on top and use a sign for the backing  -simply wonderful.

Pistons look great as Stools; and can be applied to many situations: Here they are used in The Corner Bar:

Minecraft Stool Guide