My DD (now 10) has a cabin bed (half the height of a bunk bed but with a pull out desk and storage room underneath). She's been in it since she was 8 and loves it! It has a really long solid rail on the side (DH keeps telling me we should take it down but I'm not convinced). My DD gets out of bed throughout the night as well but has always been able to navigate down the ladder ok. We have another thin mattress, and scatter cushions, lamp etc underneath DD's so she uses it as a chill out/reading/napping space.

But I'm a bit cautious of having a higher loft. They are usually much higher than a regular bunk (safety worries, more tricky to make the bed, etc) plus it's hot up there near the ceiling in summer! I'm not convinced that the space underneath would be fully utilised unless it has very well planned storage features.