Kirby is the best vacuum I have ever used.  It is a bit heavy but it is also self-propelled, both forwards and backwards.  Bags are about $2 a piece but are quite large and have micro filtration.  I bought mine on Craigslist for $100 and it had all the accessories including the zipbrush which is excellent at pet hair removal on upholstery.  I have used the carpet shampooer and the carpet is dry in 2 hours NOT 2 days.  My mother in law has her Kirby now for over 30 years and it still runs!  HIGHLY recommend.