My kids are 6 and 8. For whatever reason, they have NEVER slept in our bed since they were more than 6 months old. There was never a traumatic “Cry It Out” experience either. We just started putting them in a crib at a young age and they always understood that they had a separate bed. When they were 2 or 3 and waking up before us and coming to our room we would invite them to get into bed and snuggle, but for the most part, they were not interested.
Since they were less than 2 years old they have been phenomenal sleepers and currently sleep from about 8:30 PM to 7AM every night. They NEVER wake up in the middle of the night. I can literally only remember once or twice each when they have ever woken up.
Still, I wouldn’t them to be 2 floors away downstairs.