Steve love the fireworks photos...if you don't mind do you remember what settings you used for those two?
I shot some while at the beach using a mix of f5.6 (which I've learned probably wasn't right, should've used around f11 or so I've read) ISO100 & 400 with varying speeds from 1/4 - 4". My shots don't look anywhere near as good as yours though
I think I took shots a few years ago with my kit lens and they came out well. If I remember correctly, I prob used f/ 5.6 or so and had the shutter set around 4 or 5 seconds. A tripod and a remote go a long way with those shots.