I'm revising wilderness encounter tables. I've recently consolidated my "regular" and "Eastern" monster lists for TSR. Treasure tables, too. And now I'm working on new wilderness encounter tables.
In the past, for Chanbara, I pretty much copied what Cook/Marsh and then Mentzer did, with a table by terrain type for monster classification, then tables for each classification broken down by terrain type. In Chanbara, I also included seasonal variation for some of them. I'm not planning to go down the seasonal variation route again, but I am considering different ways to lay this out.
AD&D and the Creature Catalogue go the route of the big master list (d%) by terrain type. There's an advantage to this in that it allows wiggle room to set monsters as common or rare. But every monster is jammed onto one table, and they take up a lot of space. I'd like to be able to lay this out on two facing pages if possible, for convenience.
I have a couple of other ideas for how I could do this.
First would be to do something similar to BX/BECMI, except instead of the initial table, just break down each terrain type by monster type. So the Forest Table would have columns for Animal, Fey/Yokai, Humanoid/Giant/Oni, etc. But I'd either need to give everything equal probability of appearing, or have numbering for each column. This would probably be the most space efficient way to do it. Although I've got more categories than Cook/Marsh/Mentzer, so I'd probably want to consolidate classifications a bit more.
Second would be to divide terrain types by proximity to civilization. So each terrain type would get columns for Settled, Borderland, and Wilderness (to borrow from the Companion Set's domain management classifications). This would end up with a grab-bag of monsters on each list, but they would be more sorted into challenge levels for low, middle, and high level PCs. This one seems interesting, different, and useful, but would probably take up more space than I'm hoping for, unless each list is fairly short.
I've got over 400 monsters in this thing. Nearly everything from BECM/RC (a few I NEVER use or just don't like removed), plus monsters and NPC types from Flying Swordsmen and Chanbara, and some extra monsters from modules, 1E, 2E, 3E, and homebrew monsters from my Beast of the Week series way back when (many of the sillier monsters -- but by no means all silly monsters -- removed, so no more Saurons running around in packs :D). Of course, many of these are "dungeon only" or planar creatures, but it still leaves me with a lot to work with, and not every monster will make the cut.
I guess I should spend some time building prototypes of each system and see which one I like most.