We know clients do not always have the space to have a separate utility room, but when they do it can be such a useful room. I know from having a couple of kids that we as a family create a huge amount of washing. The separate room helps us hide away our dirty laundry and helps organise the clean stuff too.
Some clients cannot find sufficient space for their utility room on the ground or basement. They could consider putting it in the loft or taking some room from a large bathroom if available. This also has the advantage of not having to take everything downstairs, only to have to take it upstairs once clean.
We do not have pets, now the goldfish have passed on, but clients often want space to feed, clean and rest their pets. If there is enough space then the utility can be a good place to service that requirement too.

Most utility rooms have a sink, often a large sink which can be used for soaking, cleaning, pets and taking items too big for the kitchen sink. Often this will be a Belfast style sink.
If there is to be both a washing machine and dryer then they can either go in a stack or side by side, sometimes flanking the sink. They should not be too far from each other so that the washing machine can be offloaded into the tumble dryer.
To try to naturally dry in a utility room, there should be air movement, so some kind of fan and the use of a Sheila Maid is popular.
It is difficult to get a lot of worktop space in a utility room but it is helpful for organising the clean clothes in preparation for ironing or returning to their storage space.