Wow I think some people here are really missing a lot of the points I made in the OP.
The goal is to find the best EASY and CONVENIENT method of backing up ALL data daily, without taking an hour to do it.  Do you realize that, by burning CDs or DVDs, you would have to burn ALL of your documents every single day, even if 90% of it is exactly identical to the last time you backed it up?  How is that an easy way to back up at all?  The ONLY purpose of optical media for backup is for things that are huge and never change - games, movies, etc., as someone else already mentioned.
Gmail?  Either you don't understand what kind of backup I'm talking about, or you're kidding.  I can't figure it out.  Sending myself 10 MB archives to back up 20 GB of data?  Umm...no.
A fileserver in a remote location does sound VERY nice, but I just can't see swallowing $20+/month when there are plenty of good local options.  Afraid of some catastrophe occuring at home?  Just use two external drives and keep one in the car or something.
So optical = no.  Paying for a service is nice but also = no.  As stated in my OP, external drive seems to be the best option.
For those of you who use optical, allow me to ask, how much of your data do you back up?  How often do you do it?  How long does it take you?  I see no practicality to a method of backup that requires a) relying on CDs, b) does not allow you to change contents, and c) effectively creates "archives" over time instead of a nice exact mirror of your current data.
I really don't see much of a need for redundancy, either.  Even in that case, an external is still necessary.