EDIT: Sorry to those who may have already read this but I decided to redo my post.
When the word "Forest Temple" comes to my mind I imagine:
* Vines/Thorns
* Leaf Overhangs
* Plants/Fungi
* Carpets
For the first puzzle, I imagine something simple. Like Link having to climb on a vine covered wall to cross a large gap to reach a floor switch. For another early puzzle I can imagine some plant hecking to find a key amongst the foliage and of course, some traditional boomerang puzzles (suggestion: keep the first boomerang switch stationary, then have the others move).
Some "kill enemies to open door" rooms would be good too.
If I recall this dungeon features the cog that makes tornadoes, so why not some wind based puzzles too in addition?
I imagine a maze screen, and the carpet indicates the correct way.
For scenery, non-climbable vines, glowing mushrooms, pollen and leaf overhangs might do the trick. For leaf overhangs try using them close to entrances that lead to outdoor areas and don't use them at all when you are deep within the dungeon, just for a neat effect.
For the boss room, I suggest it takes place indoors. Make the room unique by giving it exclusive tiles you won't be seeing anywhere else such as thorns (
MC's level 1 boss had them on the side walls) stained glass windows and perhaps a symbol on the floor that is covered in moss.
I say the size of this dungeon should match Deepwoods Shrine's size.
Thanks for reading my humble thoughts -- good luck Blaze and to also whoever else is working on this temple!