Transimission gates are used quite often in the standard cell. there is nothing special about them, then are used for complementary signals. As both nmos/pmos are used to transfer signal the sizing can be smaller than required. You can design a mux with and without transmission gate. The sizing will different in each of them.
The disadvantage of transmission gate is routing. the nmos and pmos terminals have to be connected so it makes it difficult. In lower technologies 28nm and beyond the designs are easier to layout without transmission gates.