www.decksusa.com or a build it yourself deck off a planix program. These will allow you to use your imagination, print out plans, print out cutting lists, and a material list.
As a professional deck builder in my area, I often use a garden hose to make changable boundaries with customers, can add what ever you want where ever you want, just depends on how much homework you have done in preparation.
I always stress to customers that tree holes, multi levels, benches, planters and all only take up precious space and cannot be moved around. Get some graph paper and draw your deck to scale and cut out tables, benches, planters and all that stuff and actually plan your deck like most people plan a room with furniture.
I do not know of anyone that could plan your deck for you on line and know what you want and where you want it. This is a tough question.
Get some good programs and plan it on line and its changable and fun.