As with most things, there are many ways to approach this. The right answer for you depends on some factors you didn't include. But I'll tell you that .as files are NOT the right solution. They are not the right solution because you cannot load a .as file as a class at runtime, and if you're talking about including everything at compile time, then you're not talking about .as files containing your data, but really classes.

In general, I'd suggest separating your data from your program. That means some conceptually external data source. Whether you load from it at runtime or bundle it in at compile time doesn't make much difference.

XML is a perfectly valid approach, though perhaps a little verbose.

Are you loading these at runtime, or are you bundling them into the swf?