Here is what we have and sometimes I think it is too much. But he plays with almost everything regularly because anything I feel he doesn't use is put into the give away closet.
In the family room we have open shelves with a bin of each of these items:
Duplo blocks
Lincoln logs
musical instruments
small cars/trucks
puppets
airplanes w/ runway pieces
balls
plastic zoo and farm animals
wooden blocks
On a bookshelf in the same room he has 2 Fisher Price scenes, a push around truck, Wedgits, lacing cards, Geomags, and a few misc. items.
He has quite a few puzzles but we are getting ready to retire about half of them because they are too simple.
In his room he has a wooden train set, a small wooden doll house, a small toy chest with dress up clothes/costumes/hats, and tons of books.
And finally in the living room we keep a Fisher Price kitchen, 6 small plastic baskets with various dishes and play food and a cash register. He also has his woodden castle that he got from his grandparents. It takes up a fair amount of room but he adores it. Oh and we have a wooden chest full of board games (we play 2-3 board games a day!).
If you notice, most of my son's toys are open ended because they hold his attention a lot longer that way. If you look around his friends' houses you will probably notice that many of their toys are battery operated (which in my opinion takes a lot of the imagination out of playtime) and rather close ended. Toys like that are fun and exciting when you first get them but then kids become bored with them much quicker. It sounds like you have a good amount of toys for your kids and that you have chosen very open ended options for them. Kids will always ask for more but if they are engaging in imaginative play then they have enough.
An interesting aside...my son attends a local preschool that has tons of great open ended wooden toys, games, and puzzles. But he attended a preschool in Costa Rica for 2 weeks this winter. They had a broken Fisher Price bus, a broken Fisher Price airplane, a plastic doll house with no dolls or furniture, a box of wooden blocks, and a tub of Duplo blocks. This was all for 10-12 kids. The first day my son was complaining that there weren't enough toys to play with and just sat off to the side. The second day he figured out a great game to play using the dollhouse and some of the wooden blocks. He was happy as could be. Kids don't need much to have a great time.