I know people accumulate a lot of needles, and that I'm not the only person to bid an insanely high amount for a mixed lot of needles on eBay just to get those really cool plastic ones they only made in the UK in the 1950s (I found that out by being outbid so many times before I finally won a few.) And I definitely know that when you're the only knitter of your generation in a very extended family you are going to inherit all the needles there are to inherit.
But honestly: 12 sets of 6mm straight needles??
Here's how I used to organize my needles: "the ones I like", "the ones I will change gauge to avoid", "ugh, maybe"s, and "please promise me you will never ever knit another Icelandic sweater."
Here's how I sort them now, after three and a half hours of size-checking and folding and taping: by size. I don't care whether they're straight or circular or double pointed or what length any those kinds are, or even whether their colour is a nice complement for the yarn I'm knitting with. If I need a 3.75mm needle to get gauge, by golly I'll be able to find it.
I came up with kind of a nifty filing system after drooling over all the gorgeous organizers on Etsy and realizing I have way too many needles for any of them. If anybody wants instructions and photographs just let me know and I'll post on that tomorrow, just in time for you to spend the weekend doing the same (while I work out the pattern for the exciting next freebie, heh heh heh.)