(Resent because of bounce notification (email handling in osx is really beginning to annoy me).  Sorry if its a dup)

I used to worry a lot about strings being indexable.  And then I eventually let go of that and realized that it isn't a particularly important property for them to have.

I think you will find that UTF8 is generally the most convenient for a lot of things but its a bit like light in that you treat it alternately as a wave or particle depending on what you are trying to do. 

So goes strings - they can be treated alternately as streams or byte arrays (not character arrays - stop thinking in characters).  In practice, this tends to not be a problem since a lot of the times when you want to replace a character or pick out the nth one you are doing something very computerish and the characters you are working with are the single byte (ASCII legacy) variety.  You generally know when you can get away with that and when you can't.

Otherwise you are most likely doing things that are best dealt with in a streaming paradigm.  For most computation, you come to realize you don't generally care how many characters but how much space (bytes) you need to store your chunk of text.  Collation is tricky and complicated in unicode in general but it isn't any worse in UTF8 than any other encoding.  You are still going to scan each sortable item from front to back to determine its order, regardless.

Most of the outside world has settled on UTF8 and any ASCII file is already UTF8 - which is why it ends up being so convenient.  Most of our old text handling infrastructure can still handle UTF8 while it tends to choke on wider encodings.

-Todd Blanchard