For me, I primarily collect DT bootlegs - I'm actually trying to get copies of every show that's been bootlegged (tho I have a looooong way to go), and I am slowly making my way through listening to every single show, although not necessarily every recording since I do have some duplicates.
Aside from that, the only other band that I make a point to collect a bunch of their shows is Riverside, and even then, I haven't gotten around to listening to most of the ones I've collected...yet. Big reason why I do so for both DT and Riverside is because of the differences between the studio recordings and live performances, and that the shows/performances vary from show to show.
It's for that same reason (or rather lack thereof) that while I collect bootlegs of some other bands, I'm pretty happy with getting one or two great sounding boots per tour, rather than trying to collect a huge number. Bands like Rush and Queensryche, and even with Rush, I haven't bothered collecting any bootlegs since 2002 because they've put out an official release for each tour and with QR's lack of variety in their setlists, I haven't bothered grabbing anything since the first few shows with Todd.
In all cases, I focus just on audio bootlegs, unless there are video-only bootlegs of some DT shows. I just don't have the time to even sit down and watch official live releases from these bands, so why would I want to collect a bunch of questionably shot bootlegs? At least with audio recordings, I can do stuff while listening to them.
As for keeping track of everything I've collected, I try to keep it simple - I don't waste time with grading the recording (which is all based on personal opinion) - I just keep a basic list with the date, title (if there is one) and if there's any issues I'm aware of with the recording (missing parts of songs, etc)
The one thing that's nice these days, besides the fact that there's much better equipment for recording/capturing concerts is the fact that harddrives are so much cheaper and higher capacity. No need for keeping huge amounts of blank CDs for burning any longer.