I have four kids, ranging from 24 months to 10 years. We are homeschooling. We lean towards unschooling, so I have a very structured environment that encourages them to dive in and learn.
It may be easier to explain how I've set our house up. I tend to go with a lot of Waldorf materials (nature-based) but I like Montessori ideas as well.
We have a six room house. Two of those rooms are used as bedrooms, and there is nothing but beds and clothing storage in them, so the kids don't really play in their room (or ours).
Our family room is our "reading/music room".....there is the piano, instruments (guitars and other small items), the computer, bookshelves and seating. The books are all at their level, and they are welcome to read whatever they want as long as they put it back when they are done.
Our kitchen has a Community Playthings sink unit, which has a sink that is actually a dishpan sunken into the top. Underneath there are two doors and plenty of storage for all of the kids' kitchen utensils.....they have plates, cups and bowls, mixing, cutting, slicing and grating tools, as well as a few plastic boats, people and cups for water play. My two younger kids LOVE using this unit.....I fill it up with water, colored water or snow, and they scoop and pour to their hearts' content. My 24 month old has been using this for quite a while now.
Our playroom has a train table, a block area (dollhouse, unit blocks, small colored blocks, tree blocks, lincoln logs, plus little wooden animals, cars, people, trees and signs), a housekeeping corner (wooden kitchen, cradle, highchair, table/stools, cash register, scales, chalk board, dress-up stuff, doll clothes, playstands and a rocking/step boat) The kids stage some pretty elaborate scenarios in the housekeeping area. Sometimes after they go to bed at night I'll go in and move the playstands around to make a cafe or store....something to fire their imaginations. They also use the blocks a LOT......they make entire cities with them.
Our front room is a combination of dining area and homeschool room. We've got a big table in there, plus a 2 1/2 by 4 foot sand table, two bookshelves (that hold math manipulatives, puzzles, table toys, etc) and a 6 1/2 foot long wooden bench (picture a picnic table cut in half lengthwise). My DH cut three holes in the top and I sunk three full-sized dishpans into it, thus making three "stations". In these pans I put various things......right now there are beans in one, along with scoops, cups and a sorting tray; in the second one there is modelling beeswax; and in the third there is a magnet kit, which has magnetic wands, marbles, hardware, etc. Some of the other things I put in there are: threading beads, balancing moon game (Hearthsong), our rock, shell or feather collection (along with a corresponding guide), small wooden marble run with a couple of marbles, stacking trolls (also from Hearthsong). We also have a nook that is curtained-off from the rest of the room......in there there are tons of shelves with games, reference books, reading tools, art/craft supplies, and a small craft work surface.
When I am working with the bigger kids, my younger two kids will use these stations, the sand table or some of the table toys. Sometimes I'll put the cover on the sand table and use the top for playdough or finger paints. They also enjoy drawing/scribbling with crayons.
If I could have nothing else for my kids, I would make it a priority to have a sensory table......it is easily made by taking an old coffee/end table and making a hole on the top to sink a full-sized dishpan or similarly-sized plastic container. That way, you can vary what's in it.....beans, rice, sand, water, snow, ice, playdough, or messy toys like the magnet kit, threading beads, etc. If you use an endtable/cabinet, it can double for storage underneath. My 24-month old son has been using ours since he could pull himself up to it, and he will spend hours a day sifting sand, or sorting beans and rice, or splashing in water.
Good luck, and as I think of stuff, I'll post!