I'm only using a portion of the available planting space and that's because I'm looking at laying out the plants a bit different then in the past.
First, I have decided to layout wider raised beds and use "square-foot" gardening or a "block-style" layout with "close plant spacing." This compacts the design producing more vegetables in less area, plus it helps to reduce weeds, requires less watering and shields the soil from the sun reducing water evaporation.
This diagram shows a typical "square-foot" plant spacing in the top row, and how to apply a "close plant spacing" in the second row... yields are greater using a triangle or hexagonal layout.
Second, I have incorporated "companion planting." This is an organic approach to gardening, where by planting certain plants near or adjacent to another promotes beneficial natural results like pest control or attracting certain insects or even resulting a higher crop yield. Lots of other rewards too.
Keep in mind, these are just my layouts... for a more detailed information on a Biointensive Garden click here.