The formula for plant combos in containers i " Thriller (in the middle ) Filler,Spiller.
I have found coleus come is all sizes and shapes.
The website RosyDawn
http://www.rosydawngardens.com... has lists of coleus and what type they are. I place my order early in the year.
I tend to buy the tall ones and it seems a good idea except until now when they overpower the container.
Good fillers are calibrachoa ( superbells) they fill and spill. Wave petunias, pelargonium geraniums. I like certain varieties of trailing coleus as spillers.
Check out the tall Abigail in front of the door.