You can choose to add a 5 1/2" wide sitting ledge to the top edge of the Sonoma Style planters.
A sitting ledge allows you to sit on the planter as you work or just to create a convenient additional seating space for any reason.
The seating ledge uses up nearly 2 1/2" inches on both the inside and the outside of the planter and is not available for planter that are less than 24" W wide because they lose too much of the opening at the top for planting.
In the photo below, you can see a 96" L x 24" W x 24" H Sonoma Planter with the seating ledge:
