Speaking as someone who's husband has killed his fair share vacuums, I am very pleased with our new Dirt Devil Ultra Cyclonic Vacuum. This bagless vac picks up like a dream!
89.99 at Dirt Devil
As a mother of 3 small children (5 and under), I'm used to having to vacuum lots to keep up with all of their mega messes so this thing has sucked everything from cerial or small pebbles to the grass tracked in from outside. I've not had a single problem with this vacuum. It does have a rather small container, but I don't mind emptying it after each use, it only takes a few seconds.
I don't have any stairs so I don't have an issue with tacking it up and down, which is probably a good thing because it is not what I would consider a light weight vacuum (also good for me because it is more sturdy and holds up well to my 3 chldren trying to climb it). I also can't speak for how it would react to pet hair, as I have no pets. I do highly, however highly recommend this vacuum for use of cleaning up childhood messes. :)