So we landed on semi-transparent concrete stain. It turned out well; and it can be accented with outdoor rugs or even a patch of fake grass (which is what we did). The total cost was $300 for about 500 sqft of coverage, including tool rental and purchase - that's $0.60 a foot (way less than the $5 a foot tiles).
Unfortunately we didn't take too many pictures of the process, but we did learn a couple of tricks that should be useful for people without concrete staining experience. Hit the jump below for more details.