Foyer

I agree with acm. The foyer isn't an ideal for a play space, for the reason noted. Perhaps play could be incorporated into the family room?

for some reason I'm having issues adding pictures of the family room area, where i'd like the kids space. The foyer/hallway is 20 x 7.5 and I'm looking for entryway ideas, rugs, etc for the large space. As well as for the family room area that it connects to

you have the perfect stairway to try something like these:

as for decor, any of these looks w/a bench, chair, rug, etc will look great

Thanks!