I bought the full set of pre-painted Arkham Horror investigator miniatures back when they came out. It is great because FFG are using the same investigators in all their Cthulhu games (they call it the ‘Arkham Horror Files Universe’). You can use the figures in Arkham Horror, Mansions of Madness, Elder Sign and Eldritch Horror.

The new investigators in the Pyramids
I keep all the figures in a couple of plastic containers normally used for screws and things, and had taken out the Eldritch Horror investigators to keep with the game since this is the game I play the most and I wanted to keep them handy.
Now, with this second larger expansion, most of the investigators are available to be played in Eldritch Horror, so I am putting them all back in the plastic boxes and will keep these boxes near the Eldritch Horror box.

Putting all the investigator figures back into my containers. There are just enough compartments for all of them.
I used to be able to cram all the boards, cards and bits for the first three expansions into the original box, but that won’t be possible with the new expansion added in.

I took out the cardboard insert and could get the main board, the antarctic board and all the bits in one box. The new stuff won’t fit.
I think I may split out the cards that are specific to the adventures keyed to the Antarctic and Pyramids boards and keep those with the boards and rules in their respective boxes.
You can’t use both add-on boards in one game (unlike Arkham Horror where each town could be added on to the next and all be reached by train), so I will only be using one or the other.
I will keep all the extra cards for the base decks shuffled into those decks and store those in the main box. That way I can play the base game with all the variety of the add-on encounters and items, and if I want to play with one of the two other maps I can get all the bits for that map from its own box.
Sounds like a fun sorting project. Boardgamers love sorting stuff.