OK, here's my personal & professional (former housekeeper) position -- can the upright vacs. Seriously, unless you're dishing over mucho $$$ for a Kirby or something they're just not worth it. And even a Kirby doesn't work as well on hard floors as a canister vac does. You really, really need a hard floor attachment (ie: a seperate head with bristles but w/o the big beater bar) to get non-carpet surfaces well. Also, I really, really dislike bagless vacs. If you have any allergies at all bagless is not the way to go.
Now, depending on your budget I'd recommend 1 of 2 vacs:
Higher price: Electrolux canister. These things are awesome. My Gram is still using the one she bought in the 50's! My Mom has two -- one for the basement that is older than I am (so like 32) and a newer one that she uses in her main house. They don't cost anymore than a Kirby, hold up well, are relatively easy to get parts for, and most importantly they WORK.
Lower price: Kenmore canister vac from Sears. I'm on my 2nd one of these in 10 years. My first was purchased at an auction & we used it for 8 years before it died on us. Got a new one last Christmas & don't plan on having to get another for several years. Mine has a HEPA filter & great dustless bags. It came with the power attachement to do furniture & stairs with. This is the one I have:
http://www.sears.com/sr/javasr/produ...seBVCookie=Yes
We have 99% hard floors (DD's room is carpet & some throw rugs) & the hard floor attachment works works really well. I've even been passibly happy with the way the power head does the floors, which is more than I can say for any upright I've tried.
HTH & good luck!
Holly