Continuity is golden! It makes a statement that the job was either done professionaly or a bone-head LCO got a "good deal" on a hodge podge of plants and just stuck them in the ground at random. Repetitive use of the same plants through-out the landscape is much more appealing. Find a hand-full of plants that compliment/ contrast with one another. Stay away from straight line plantings, think.......... curves(not too radical),large flowing serpentine arcs, tall plants in back followed by med. then shorter in front. Allow room for the plants to mature within your mass plantings, otherwise they'll be crowding one another in a few short years.
I haven't messed w/ any landscape programs. Sounds like the customer doesn't know an Indian Hawthorn from a member of the Blackfoot tribe. Give 'em a estimate not to exceed $xxxx.xx, have them sign the agreement, and have at it.