My DD is 18 months and 32 inches tall and is starting to brush her own teeth. We might even pt soon. The bathroom she will use is small and we all use it during the day, so it would be better if the stool was reasonably moved or thin or at least not something you find yourself tripping on all the time. A quick glance on Amazon reveals Elmo and similar stools--but I'm not sure she'll like Elmo when she is 5 and still cannot reach the sink. Some small stools seem like they wouldn't work because they are too short. There are a few cute 2 step wood ones, but the prices are ~$80. There are some folding ones, but then the reviewers are like, "my toddler had to go to the ER when this collapsed." Do you have one you like?
Re: step stool for bathroom?
I have this one too and it is perfect for my 2 year old (since 23 months) to reach the kitchen sink.
For our bathroom I also have a folding one similar to Kikkerland Rhino Easy Fold Step Stool, Short, Black which is more suitable for the bathroom height counter.
Love them both but as for ER visits, well I wouldn't let my kid used them unsupervised (not that these parents did) and I feel both are very sturdy. Also, DD seems to LOVE stepping up on them which is great incentive to get her to wash up.
As for space, if you're short on it, just stick the stool in the bathtub or shower when not using it.
If you like the Elmo one, why not get it? In a few years if she's still using it, you can always update it with some paint.