a 4x4 plot is just the size of a single "Square Foot Garden". It's a technique that can help beginners get successful results. Here are some links that can help you choose your layout, whether or not you choose to use the SF method.

http://forums.gardenweb.com/forums/load/sqfoot/msg102140054308.html?89
http://www.squarefootgardening.com/NeighGarden.htm

Note: one summer squash or melon plant, left untrellised, can cover over 6 square feet of dirt. One tomato plant can lay over 4 - 5 feet. Trellising your plants will help you get a much better yield...and that goes for vegetables and flowers. Why not have both?

You might also try reading John Jeavons's book, How to Grow More Vegetables and Fruits, Nuts, Berries, Grains, and Other Crops than You Ever Thought Possible on Less Land than You Can Imagine: a Primer on the Life-giving Sustainable Biointensive Method of Organic Horticulture. I borrowed a copy from my local library and am reading it now, and getting lots of ideas for our small urban community garden plots. I'm also learning a lot about how to take care of and build up the soil so that what I do choose to plant will have a better chance of producing more food.