I second your choices. I love the apocalyptic zombie movies. They have a kind of Red Dawn feel to em (which I also love).
This is also why I liked I am Legend to a lesser degree.
28 Days later seems like the best to imitate. Done on a fairly low budget I believe and came out great.
28 Days Later and sequel are not zombie movies. They are stories about a viral sickness, not about the dead coming back to life. The infected are not dead and potentially can be cured.
I suppose in a literal sense, but really, how do you define life when the dead things are walking around and eating? Doesn't un-dead mean "not dead?" Seems like a technicality or minor plot point to me.
Runner up, for me, would be Dawn of the Dead (2004). Resident Evil isn't bad, either.