Upstairs. All the nappy paraphernalia is up there so it's just easier. Though if someone's babysitting I usually leave clean nappies/wetbag/changing mat downstairs so they don't see how messy our spare room is
Erm TBH I dint think I've ever thought about it. Both?! We font have a bathroom upstairs so they have to be bought down stairs to be put in the nappy bin anyway. I guess first change upstairs then the rest downstairs I keep my nappiea upstairs and bing one or two down at a time. I keep my washable wipes downstairs stairs and 1 pack of disposable wipes up stairs for emergencies and any night changes which are fee an far between now. As baby comes up to bed with us at 11.30 so we general do her then and DS goes to bed at 7.30 so last change after his bath. My bathroom isn't big enough to do a change in so it has to be in the lounge or hall. Stupid 1920 house. I'm sure your find what will work for you if you change the opposite side of the house to your bathroom you can always keep a monkeyfoot wetbag there to save you going with the nappies however I think I would find sposies worse as you have to take them out side to the bin (I couldn't have poop in my kitchen). Good luck
downstairs I have a changing station in the bathroom, did change upstairs when she was little on a cot top changer. I only like to change in one place because I think it's good for their routine and linking nappy changes to bathroom ready for potty training
When Max was tiny and needed changing every 1-2hrs I did it downstairs as that was where I spent most of the day with him. Once he was older I used the cot changer more and changed him upstairs 9 times out of 10. Also all his nappies and the his nappy bucket is kept upstairs.