Precut benches are available at the touch of a keyboard, but can be fragile and the lumber often lasts only a few seasons. They're "one size fits all gardeners." Reinforcing premades with extra braces and coating with exterior stain or polyurethane extends the life of the bench.
For the countertop, leave half inch gaps so soil does not accumulate in the breaks. Add a shelf below for storage of flats pending their relocation to pots and beds.
At the side, include a storage bucket for long handled forks and spades. Drill holes for drainage.
When friends visit, brush off the top and break out the ice bucket. Voila, an outdoor bar!
Just don't get potted.
More Articles of Interest:
Container Gardens -- Pots on the Spot
Four O'Clocks and Hollyhocks
Gardeners of the Court -- The Cycle of Life in the Garden