I was in your boat a few mnths ago- now you should see it. One thing that I always tell us Urban dwellers is invest in a few good vines. I have a metal grid on my balcony and really like to have my privacy, which is hard living in an apartment. I am growing clematis and passionflower, I just need to be patient for it to cover everything. Get a few big pots and buy what you like. Combine low groundcovers with bulbs and its beautiful! If you want to get a head start, just buy some premade pots, well worth the money at your nursery or grocery store. They construct them beautifully. Get some hanging baskets too. Done!! Let me know if you need some other suggestions. I love what I have done to my once "sad" balcony! Good luck and have fun!

Sixteen square sounds huge to me! (My balcony is 4x8) :)

If you can get ahold of "The Essential Garden Book" by Conran and Pearson, it has a nice little chapter on small-space gardening and some visuals that might give you some ideas on what you can do with this space. (Though beware, the rest of the book contains a lot of acres-vast gardens that will inspire all sorts of jealous fits.) Another good one is... oh what's it called... "Small Gardens for Modern Living" (I think.)

You can really do great things with this space. If you have any windows overlooking it from above, you might consider grouping your containers into shapes you can enjoy at that angle, too.

What are the specs - how much light do you get? Is there a wall around it or is it open?

You might want to consider how much sunlight you get, prevailing winds, winter-time temperatures, and any condo restrictions on wall-mounts, ceiling hooks, etc.

I like my container water garden -- around ~30" diameter plastic pot on a sturdy plant roller, with 2-3" of clay soil with 2-3" of pea gravel, a container hardy water lily, underwater grass (sagittarius, acornus), duckweed, and water hyacinth. No pump, no fountain (drought restrictions!), just a screen in the hot months over the top to prevent birds from drowning.

Some shutdown required for winter storage, but not much fuss!

Try also a mix -- climbing vines, taller plants, shorter plants, groups of small round pots around larger round pots, large rectangular pots, etc.

Do you want to attract birds? Butterflies? Certain container plants will attract wildlife. You can also add a birdbath...

Have fun!

I'm in the same dilemma spacewise, with just half of a shallow yard backing up onto the alley -- but there's loads you can do!

This was taken last spring; as the summer goes on the clematis completely covers the fire escape, up to the middle of the second story. (And I cleaned up the pots some!)
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This shady nook is now completely filled in, and reached for the top of the fence. The sweet autumn clematis to the left is blanketing the fence. The mock orange along the porch steps to the right is just passed bloom now, but was smothered with white. The casablanca lilies are topping out at about 6', the toad lilies and the heuchera are starting to put out their blooms, and as always, I'm ready to swoon with the scent of the royal standard hosta....
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Alison, great gardens! I love how the clematis goes up the fire escape.

Kszal, thank your lucky stars you have as much space as you do! You can do all kinds of things in a space like you have. My balcony is 4 1/2 by 26, like a bowling alley. Wish I had a 16 x 16 space!