The size you choose depends as much on your preference and height as it does on the space in your room. If you sleep alone then any size can work. For couples however, there are full size, queen and king sizes, as well as dual kings (made up of two extra long twins). Taller people may want the longer California King, while larger people may prefer the width in an Eastern king.

Mattresses are made in traditional innerspring materials as well as new space age choices that range from memory foam to air. Each style has its devotees. Ask your friends what kind of bed they sleep on, notice comfortable beds when you stay in guestrooms, and do some preliminary research on the Internet to help you learn the terminology and give you some info on mattress specs.

Manufacturers are adding more layers of foam and padding to mattress tops which add softness and comfort. However these pillow top mattresses can require extra deep fitted sheets and bedding. Be sure to account for the actual depth of your mattress when you go to purchase a comforter, mattress pads, and sheets.

Some people love a nice firm bed while others prefer softer "pillowtop" mattresses. As long as the overall support of a bed is good then either "feel" can be fine. Do you and your spouse argue over how firm the mattress should be? Consider a dual king (two separate twins pushed together) or beds offering adjustable firmness on each half.

Bed frames (the metal structure that holds the box springs and mattress up off of the floor). Beware of cheap ones in lighter weight metals that may wobble or become flimsy with use. Better models have higher quality casters and heavier, more stable construction. Buy a good one and it should last for decades.