What kind of focus are you looking for with this deck?
It looks like you have big tokens, small tokens, big beaters, and lifegain all going on at the same time. To line up with Trostani, I'd probably cut many of the big beaters and start playing less of the small token guys, and add more of the big token makers.
GW is by far my favourite colorcombination. Back in the old Ravnica days the first deck I built was a Selesnya token deck. So it comes without saying that I really like this kind of deck (Altough I play Ghave myself).
I like the lifegaintheme and I think lifegain in general it is a bit underestimated in this format but a card like Heros Reunion, that does nothing else is just bad and should be cut. I'd also cut Solemn offering for something like Aura Shards.
I am putting together a Trostani EDH deck and one card I am considering is Mercy Killing. Oh, you want to Oblivion Ring my fatty? POOF! Now I have a mess of tiny token dudes, plus the life gain from Trostani, and even more token dudes and life gain if you have Doubling Season or Parallel Lives on the board. Would be a great combo with Wurmcoil Engine or Worldspine Wurm for the added token baddies that appear when they hit the graveyard.
EDIT: Just noticed you don't have Wurmcoil Engine in your deck. Um, you really need Wurmcoil Engine. FYI.
Made another quick change. I swapped Heroes' Reunion for Avenger of Zendikar. Personally, I like gaining 7 life (14 with Rhox Faithmender out) for 2 CMC, but I already have enough lifelink in the deck and that's all it does.
Wurmcoil Engine would definitely be on-theme, and Worldspine Wurm would be nice...assuming you can easily get to 11 mana. Although, you do have a relatively high curve already. Have you looked at lowering your curve at all?
Eternal Dragon doesn't quite fit your theme, but he's a plainscycle for 2 colourless, and can be reused later as a flying body that always comes back into your hand (provided you have the mana). I found him very useful in order to fetch duals or even normal plains. Mikaeus, on the other hand, never really worked for me, as he was always too slow.
I finally put my Trostani deck together on MTGO last night. I made a list yesterday but I left it at the office, so I had to wing it based on what I could remember. I will post my deck list in the next couple of days.
Anyway... Played one game 1v1 and won. The MVP for me was Kazandu Tuskcaller. I got her going early and often, spinning off as many 3/3 elephant tokens as I could. Leveled her up all the way and I was dropping two 3/3 elephant tokens and gaining 6 life each turn off Trostani.
I hear the CMC concerns about Worldspine Wurm, but my way around that is Elvish Piper. I also run Fauna Shaman in there, too. Of course, I haven't seen either of them in action with this deck yet, but I'll report when I do.
Another card I run to boost my creatures is Wilt-Leaf Liege. 4CMC hybrid mana gives you a 4/4 body, with +1/+1 to all green creatures and +1/+1 to all white creatures. In other words, this guy gives a +2/+2 bonus to any green+white creatures, like Trostani.
I would replace Chromatic Lantern with Selesnya Signet. The signets are all good for mana ramping. Lantern is a decent EDH card, but not really necessary in a two-color deck.
I would drop Baneslayer Angel, too. She is awesome, no doubt, but doesn't really work with the the other cards well. Pardon my sports analogy, but she's like the high-scorer on the league basement dweller. She's flashy and can score you some points, but she doesn't really make her team(mates) any better.