Superhero room remodel ideas

When Jake transitioned out of his crib 2 years ago, we gave him an animal themed room (which you can see here); and even though I specifically chose decorations that weren't too "babyish" so that the room could grow with him, the room has looked babyish to me in recent months.  The best laid plans, right?  I don't feel too bad about having to change the room so soon, because whenever Liam moves to a big boy bed, he'll inherit all of my hard work on the animal theme :) 

I'm going to go with a superhero theme because I think (hope!) that might stick with him for a little while before he outgrows it.  And my plan is to just find a solid color comforter that we can just continue to use once he's moved on to other ideas. 

Here are some of the ideas I've been thinking about; his walls are yellow, and he has a red Pottery Barn anywhere chair, so I feel like just doing a general superhero theme with lots of primary colors will be easy to blend into the room. 

I only have a few things so far, including these metal, vintage-looking signs that I picked up while in NYC a few weeks ago (gotta love bargains from street vendors!):

I also scored this Spiderman trash can from Target the other day, marked down to $4!!

 Other items I'm considering:

I did these free printables for Jake's bday party and had them on the front door; I'm thinking they might look cute if I printed them out as 8x10's and framed them in white frames?? (just one of each, obviously, not 12!)

This vinyl decal from VinylKrazy is a must ($10!), I love this phrase and it's so perfect for him (I'd probably order in red or blue):

Bedding options:

Mainstays Bed-in-a-Bag ($30, walmart):

Mainstays reversible comforter set-comes in blue and red ($24, walmart):