The 2e book Oadenol's Codex has some Celestial Demesnes in it. However, for some other ideas...

Solar: An underground grove where there grow impossible trees whose fruits glow with sunlight, providing nourishment for all manner of plants. A mountain meadow filled with buttercups whose grass causes cattle to grow mighty and strong, but also judgmental such that they will suffer only virtuous handlers to deal with them.

Lunar: A marshy region where the pools always hold the reflection of the moon by night, and where one can catch glimpses of those who love them in those...