I'm a classical music lover as well. It was quite some time before I put rock or anything else in my queue. I have something like 26 days straight of classical and romantic era music in my iTunes. Now, I don't yet have an iPod (seems impossible in this day - getting one soon), but the issue I suppose is an iTunes one. I'm subscribing to this topic to track the answers I hope you get. But alas I have no solution other than greater care than you're already surely taking...
Early on (back in OS9) I wanted to keep my music organized, preferably sortable by composer or opus or type (and work number within type). This would suffice. What I eventually arrived at was a 'taxonomy' that I apply to all things - well almost nothing escapes it. It's not a very techy solution but it has worked for me. What was a nice surprise: when 'smart playlists' came along my method fitted nicely. I have folders of composers, ancient music, concertos, just piano concertos, symphonies, you get the idea.
I noticed that iTunes always would organize things by 'artist' (and in the early days there was no 'composer' category anyway. So, the idea of putting performers in the 'artist' slot went out the window. What use is it really to a classical lover anyway; put those names in the comments, append a mnemonic to the end of the 'album' title if you like. The 'artist' is always the actual composer with me, in rare cases the arranger.
From here it gets lengthy.
I was going to attach a pdf of one of my composer folders, but I don't see a way to do that here. Is there a way I can get it to you? If not fine, but I have to go now. I could return and describe in post my conventions, but honestly it represents work. I understand perfectly if you haven't time or interest - I've been doing this pretty much all along, and can only imagine what it would be like if I hadn't and now had to go over everything... Yuck.
Best wishes.