Another idea we did have for E was a set of red (or another color?) tools that are real--that have some weight to them. She seems to really enjoy how things work and would probably like to work on real hammering and what not.
For Z, it's a bit harder. There are these weighted baby dolls that seem really nice, but I don't know if she'd appreciate them or not? They are remarked on as being very realistic and calming--2 or 2.5 lbs and more like holding an actual baby.
Some games/puzzles/crafts are also on the amazon wishlist we have for the girls. If we don't get one particularly strong gift, we'll do a few smaller ones. Or maybe less? (After all, we're working on that.)