If you think that GRR is too large, busy and expensive I'm not sure that the Detroit or Chicago airports are a solution. To reinforce what the prior post stated, here are some numbers from the airports' respective websites. Some of the numbers are a couple years old, but they help give a perspective:
Gates: GRR-12 DTW-145 ORD-182 MDW-43
Annual Flight Ops: GRR-87,000 DTW-452,616 ORD-972,000 MDW-253,000
Parking/Spaces: GRR-$9/day; 9,850 DTW-$10/day; 19,000 ORD-$9-17/day; 22,300 MDW-$14/day; 6,300
Annual Passengers: GRR-2.2 mil DTW-2.5 mil ORD-76.5 mil MDW-17.5 million
As for the random screening, there's no way around it. If they're selecting every eighth person or everyone in a blue shirt, you're just as likely to be that person at any airport.