The only thing I can think of that you should buy new are big screen smart TV's, other than that, if you can find nice quality second hand anything, that works great! If you can't find what you want Wayfair.com is a great place to puchase bedroom headboards, dressers, entertainment centers and dining furniture.
I would suggest leather(real leather, not bonded) furniture for the living room. Reclining furniture is a plus. Must have comfortable mattresses. We just stayed at a house that I thought the matress was so comfortable, when I checked to see what make it was, it was a memory foam topper(sleep innovations, 2-3" topper, put that on my list for future purchases) Nice soft sheets, soft blankets, nice pillows for all preferences and have at least 3 per person available. Cotton towels. Put shelving in the showers to hold shampoos, soaps and razors(Command) makes great shelving for these accessories(Command Shower Water-Resistant, Clear Frosted, 1 Caddy, 4 Strips (BATH11-ES), 4.8 x 11.3 x 6", https://www.amazon.com/dp/B00H... ), makeup mirrors. supply in the kitchen anything that you would use in your own home. I have done this for 3 homes, sq ft 1200-1700, cost between 10,000-15,000(1/2 of all puchased second hand). We did the last house in 10 days non stop(relaced floors, repainted throughout, furnished and accessorized). Just consider whatever would make you comfortable a good choice.