One of the good things about living with bunnies is how (relatively) clean they are. After a few days in their new home, they will generally litter train quickly and stick to it. Once settled in, toileting transgressions in neutered rabbits are rare and usually about territory, such as when other rabbits are nearby or there are strange smells, both of which will trigger a need in them to re-mark their area.
However good your little fluffy ones, a significant amount of your bunny-related time will be spent cleaning up after them. Litter trays will need to be cleaned out daily, their shed/room etc will probably need cleaning every week or so. Even if they don't make a mess, dust can be a problem in their delicate airways, so regular vacuuming and wiping surfaces is key to keeping their environment a healthy one.
Even if you are planning to put the responsibility of cleaning onto your human children, their work will need to be checked and managed. The bunny wee will need to be scraped and cleaned thoroughly from the litter trays (and possibly nearby corners) to avoid germs and bad smells developing - what kid wouldn't want to short-cut this with a half-hearted job to go and play instead!