When our son was a tween, we let him have a loft bed. He loved it, and his friends thought it was the coolest, which made him love it more. During his freshman year, we moved across the country and he no longer wanted the loft bed, saying it felt too "little kid-ish". We didn't regret getting him the loft bed, though—it was good for the tween years, then we redecorated for the teen years.

Maybe do one with a queen sized mattress so when they’re ready to move on you can use the mattress and bedding.

A teen will want to redo her room no matter what she picks now, so don't invest in furniture thinking it's forever.

If you go this route, who will be changing the sheets every week? Make it easy for whoever does it. There are many, many gripes from homeowners and AirBnB hosts about changing sheets on loft beds: twin is easiest because you can wrangle a lightweight twin mattress far more easily than a double/full mattress.

Loft beds are cool as a tween, but not cool as a teen. I don't recommend it. You get more floor space but they're often visually huge so the room feels smaller.

My 4 kids swapped rooms and redecorated so many times; the rule became--"the furniture stays with the room--and the decor cost and work is all up to you"

my boyfriend in college had one, and he loved it (made the space below much larger), and I didn't mind it either. so doesn't have to be a thing that is outgrown...