We are reorganising our 3 storey terraced house after 11 years of living here.
On the second floor is a bigger double, a smaller double, a very small single and a bathroom. DH and I had the bigger double with his WFH desk in there added, DS1 the smaller double and DS2 the very small single.
On the first floor we have a small double with en suite, which has always been a playroom/teens room and everyone had access to the shower in there. It was great having a second bathroom when needed and worked well for those years. DS2 used that room a lot as his bedroom is so small and our living room is quite small too, so it gave him extra space including a desk.
We are in the process of a grand bedroom swap as DS1 is going to uni in September, DH is going to be WFH permanently and we liked the idea of having the en suite.
So far we have redecorated the 1st floor teens room, made it into our bedroom and moved all our stuff in. I love having an en suite for the first time in my life at 53. It is much smaller than our old bedroom so it really is just our bed, wardrobes and chest of drawers. But we love it and it is great that DH's desk is now in a separate room. We moved the other teens room stuff like sofabeds and bookshelves up there too, so the teens can use it on evenings and weekends.
Next move is DS1 and DS2 swapping, so DS2 can have the bigger bedroom for 6th form. DS1 is going to need to have a big clear out, but since he's going to uni it is a good idea anyway. We recently got a desk in DS2's tiny room, but had to remove a chest of drawers so he now only has a bed, a small wardrobe with hanging space at the top and drawers at the bottom, a bedside cabinet and lots of IKEA underbed storage boxes. DS1 will inherit all of this and will have to fit in what he keeps from his bedroom after the planned clear out.
If you want to stay there a long time think about where the kids will have space to work. Mine both got to an age when they wanted their own desk in a quiet space to study, especially for GCSEs and A levels. They liked this in their own bedrooms as they could do timed practice exam papers with no interruptions. But if you're not intending to live there that long it probably doesn't matter. But I would use a house for your needs now, if you like it like that, someone else will too when you sell it.