In-laws went ahead and purchased a nice cot for their spare bedroom. One of the nicest, and surprising, purchases they made for the setup was an Omega change table: https://lovencare.au/product-category/changers/ It would normally not be on our radar (we have a nice wood change table, very large with storage) however after one day we considered getting it ourselves. The storage was easily accessible and handy to refill and the mat secure and high enough to not require bending over. The wheels was so handy as when we would visit we would be moving it between rooms and sometimes within the room to cater for our travel bags and accessibility. On activity mats we went for the largest we would find that was available at this point in time: https://www.amazon.com.au/dp/B004RREJVS We liked the size (compared to cheaper Kmart and Ikea brands at the time) especially as our baby grew from 40th to 80th percentile after 5 months. On hardwood floors we supplement the base with a soft blanket i.e. the one included in the hospital Gladys bag and on carpet it is not necessary. The sides provide a little bolstering and we still use it several months later both at relatives home visits and our own. We match one of our Kmart 2m x 1.5m playmat with this playpen of the same dimensions: https://www.amazon.com.au/dp/B0F3XZTZ9F It inserts perfectly, feels secure and has enough space to for two people and our baby to be inside at the same time. Other items we sometimes bring on visits when we want our baby to be contained when we are in the kitchen or some other activity close by include Ingenuity 2-in-1 baby base: https://www.amazon.com.au/Ingenuity-Booster-Feeding-Floor-Self-Storing/dp/B0BS24CDQQ/ Or Ergobaby 3-in-1 bouncer with travel bag (easily found on used market): https://ergobaby.com.au/collections/bouncers
