IME the large featherdusters are more sensitive to nitrates than mushrooms are. So you might want to cross them off your list. First thing you should consider is whether you have enough lighting to even consider mushrooms or polyps. What wattage do you have and what type of bulbs are they?
Next you have to consider what corals are able to withstand your higher nitrates (which will continue to rise as your fish grow), and lastly you have to consider if any of these corals pose a danger to your fish. The last sounds weird but this is what happened to me. I had a nice volitans lionfish. At the time he was maybe 7" or so in length. I had trained him to eat "dead" foods and he was such a glutton that he would even take flake if the pieces were large enough. One day as I was leaving the house I noticed that one of my mushroom corals had detached from it's rock and was floating around the tank. I figured I would attach it when I got home. Well, when I got home I couldn't find the mushroom but the lionfish had a suspicious bulge in his belly. After that he became very, very ill. Went dark, stopped eating then he began to pace the tank. Night and day he never stopped. About the best analogy I can think of is a horse with colic. Going round and round trying to leave the pain behind. This went on for 3 MONTHS. Then he finally stopped. I noticed a very hard type of fecal matter in the tank (I'm sure he finally passed it). Even so, he would not eat and I had to almost force feed him, but he would only take very, very small amounts. After that he became susceptible to every illness you can imagine. Cloudy eyes, fin rot, ich, excessive slime, etc... I ended up having to put him in a QT almost permanently but in the end, the tank broke and he died.
Moral of the story? Never, EVER will I recommend having a 'trained' lionfish and mushroom corals!!
IMO instead of live corals which may or may not live in your tank (again, your nitrates will only rise as your fish grow), why not consider some fake corals? There are some really nice ones on the market and you never have to worry about dosing, or lighting, or waterflow or whether your fish want to eat them or not!