You know, I wonder what the hunting reserves would look like if you ever got to those. The fact you've often mentioned fern praries and conifer forests makes me think that one of the reserves is a lot like Morrison's Maze from C+.
I've had some rough ideas in mind. Nothing too detailed yet, just some general biomes: fern prairies, conifer forest, desert. Maybe a more desolate area similar to the Great Lake. I suppose I'll have a clearer idea later down the line.
Ooh, expandable vocal sac! Love the feathery mane and colors, too!
Idea: Funnily enough, you already used what I was going to suggest, but I'll suggest it anyways. For hadrosaurids, such as Olorotitan, Brachylophosaurus, Saurolophus, Kundurosaurus, Gryposaurus, and Jaxartosaurus, maybe their brightly colored crests help with communication between species, but the males have expandable throat and nasal sacs that they display during the mating season, not unlike how frogs find mates by chirping the loudest (just scale it up a million times or so).
Additionally, what if some species of hadrosaurs (or smaller dinosaurs) were given zebra-like stripes? Given how it seems they have little other way to defend themselves other than to simply run and hope someone else gets eaten, maybe they'd have stripes to make it difficult for predators to select an individual out from the running herd.
For microraptorids, such as Wulong and Tianyuraptor, maybe some of them could have extravagant feathers like those seen on peacocks, quetzals, or birds of paradise. It's becoming increasingly apparent that feathers were used for more than just flight and warmth among dinosaurs, so why not let the fancy things show off with plumage on par with some of the crazy bird brains of the modern world?
For iguanadontids, such as Camptosaurus or Dryosaurus, how about giving them a mean of protecting themselves? While these examples are fairly well known, they're usually portrayed as the poor, helpless prey that gets torn to shreds by the more exciting stars of the dinosaur documentaries you see and to be fair, they haven't shown much other means of defending themselves besides running. At least in regards to Dryosaurus, it's been suggested that they might have also burrowed, but that does little to defend themselves when they're caught out in the open. Funnily enough, I looked up a pangolin skeleton, and I discovered something interesting - those famous scales that cover every part of a pangolin's body aren't part of the skeleton. Meaning that there's at least a fair chance that some dinosaurs - such as poor Camptosaurus and Dryosaurus - could have defended themselves with scaly armor!