Alex,
I too agree on the need for a ceiling. However, rather than suspended, I'd go with regular drywall fastened to the joists with screws. If ductwork , piping, or electric wiring runs along the bottom of your joists, just add wood spacing blocks or runners to the joists. Doing that will essentially extend the joists below those utilities so you'll have something to screw the wallboard onto. With a 9 foot high space you can most likely lower the ceiling to 8 foot without feeling cramped or boxed in. That ceiling will not only cut down significantly the possibility of dust drifting down from above over time but another advantage would be if there should ever be a leak from any of those overhead water pipes, instead of it dripping or spraying directly onto the layout below, the wallboard will help catch and diffuse the water and hopefully, providing the water's not gushing out, you'll be alerted by any visible water stains on the ceiling to tend to it immediately before it becomes a significant and major problem. Also those interlocking foam floor tiles are a great idea since they'll not only provide cushioning for your feet and be kinder to your knees over the years ahead but they will provide a layer of insulation over that cold concrete slab floor.
