Flower Forest's aren't really that exciting. They're just a plains biome with a couple of flowers (this isn't meant to be an insult or anything I love flower forests but I think they need an update).
I know better terrain will come in the next update so I won't mention that but I think trees with coloured leaves and a new mob (maybe mooblooms?) would make it more exciting to explore.
The tree with purple or pink or orange or blue leaves would for builders and terraformers add more motive to go there
And a new mob would just be a bit more interesting. I think mooblooms kinda feel vanilla, I mean we have mushroom cows and glowing squids, flower cows aren't that crazy, and would just be really fun to have in the game