The latest thing in commercial vaccuum cleaners is called a "Back Pack Vac", which is a vaccuum cleaner you wear on your back very much like a back pack. These are good for hard floors, but they're not great on carpets because they don't have an agitating brush. You need that agitation to remove solid dirt from carpets like sand, skin cells and pollen that falls into the carpet pile.
They're expensive, but they're powerful and quiet, and they eliminate the problems associated with having an upright and not being able to vaccuum up elevated surfaces (like tables and workbenches), or having a canister vaccuum cleaner and having to pull it around furniture with you everywhere. Back pack vaccuum cleaners go everywhere, and you just need to bother with the cord, but they're very versatile, which makes them popular amongst people who clean for a living.
'Backpack Vacuums - Vacuums -?The Home Depot'
Whatever you do, don't fall into the trap of buying a mini-carpet shampoo'er like those sold by Bissell or Hoover or Eureka, thinking it'll get your carpet cleaner than a regular vaccuum cleaner. Carpet shampoo'ers are meant for removing wet or dried up liquid spills on carpets, not solid soils like sand and skin cells and pollen. The problem is that once you get the carpet wet, the surface tension of the water will make it much harder to remove the dirt sticking to the carpet. Next time you're at the beach, try cleaning sand off of wet feet and dry feet and see which one works better. So, if you want something to clean dry solid dirt out of a carpet, stick with a vaccuum cleaner with powerful suction and an agitating brush.