I really like the use of corrugated roofing material--it goes perfectly atop the great little terminal and the overall effect reminds me of some of the famous Frank Gehry projects (think Guggenheim Bilbao, the Disney Concert Hall in Los Angeles, or the Case Western Reserve University--my dental school alma mater--School of Business Management Building). At any rate, regarding the grass, you might consider keeping what you are already using, but then experiment by dabbing on hundreds of tiny dots in lighter and darker shades of green onto the grass, which would eliminate the current monochromatic effect. If that still isn't realistic enough, or if it looks bad, then you could switch to "Plan B" and use your more expensive turf, or alternatively, SNOW!!.
I think it is cool to have an airport in Wisconsin's Great Northwoods--I spent many childhood summers--and some awesome winter/ Christmas holidays--up there
In those days, it was quite an ordeal to get all the way up to Rhinelander, but truly worth the trouble.