I didn't want to hi jack another thread that was asking about coffee and end tables so I thought I'd start a new one.

My question is, how high does an end table have to be? On a sofa with a rolled arm, should the table be below the roll, in the middle or even with the top of the sofa arm? Also, do the rules change for height depending if the table is round square or oblong?

Just want to know so if I decide on one end table for the living room, I'll know what height to buy that will be appropriate for the new sofa.