With regard to fireworks, my DS age 9 loves the visuals of them but not the noise. We solved this by using foam earplugs with DH huge hands clapped on top of them. DS can now enjoy Illuminations, Fantasmic and the MK Fireworks shows! He was obviously very pleased with himself once we found a way around the noise factor. He knew he was missing something special.
We have a tendency to strongly encourage our son to try things he appears to be afraid of -- many times he is just seeking confirmation that it will be all right. He was terrified at the thought of Test Track so we "bribed" him with Spaceship Earth -- "first TT, then SE." He was okay with that and now TT is one of his favorite attractions.
Only you know what is best for your child(ren) but my approach is to nudge DS out of his comfort zone ever so gradually. The results continue to amaze us.