A 24' ladder will be fine. Keep in mind while a longer ladder is a more stable when it's not extended far, but it is heavier, and if you're moving that ladder around all day the added weight takes its toll. A type 1A 24' ladder is rated for 300 lbs. and is nice and stable, unlike the typical homeowner grade garbage ladders are. If you're over 300 lbs, or afraid, get a type 1AA ladder, that's rated to 375 lbs. Type 1A and 1AA ladders aren't cheap, but they're worth it if you use a ladder a lot.