First, ask yourself "For how long do the kids play within each area/toy collection?"
Kitchen play
Cars
Dolls
blocks
...what else is there that they play?
Next, I would try to see how the toys get played with, and by whom?
Something to consider:Toys that one child prefers to play with independently, I would actually move those toys to the child's room. Kids need invitations to play in their room and take alone time each day, so if you have a son that likes to play cars/track by himself, that's where he should do it. This is not a punishment, it's about keeping group activities in the common areas and single-player activities in areas more conducive to this sort of play. You don't have to do it this way, but it's something to consider.
Another thing you can do is to just cut down on what's available. Instead of having 30 Hotwheels cars out, let your children pick out 10 and put the rest away. Let them know that they could change out their cars once a week, but that you have a maximum of X amount of cars per kid at one time. Do the same for the mini-kitchen toys if you feel like you have too much available. Let them pick out some and store the rest. Store the 'extras' in marked bins in the basement, attic, or under the bed in your room or in the garage in plastic bins. Or put the bins in large, marked paper bags and hang them on nails in the garage, up against the wall. (I was unsure if they couldn't go into another room due to storage or preference).. We do this at our house and my son loves it when he can 'go shopping' or 'swap out' toys.
For dolls, I would sort by type, with each type's clothes, and have a small variety available at any different time. If dolls have their own select clothing, consider storing the clothes in the bottom of the box, cover with a small 'blanket' (scarf or fabric scrap) and use those as 'beds'. Store extras covered.
Small sets (polly pocket, legos, etc) should be stored by type. Limit the number of 'smalls' as well.
Flashlights, binoculars, kaleidoscopes, cameras-- a 'vision' box.
Dress-ups do well in a fabric bag or basket. Pare down to the most open-ended costumes.
If you are wanting all the storage in just one place, consider a piece of furniture which would facilitate that. IKEA has some shelving into which fabric boxes fit, and this might do for your needs.
Honestly, since I am not in your house, it's harder for me to go on from here. As a nanny, it was often my job to organize/sort out household playrooms and toys and arrange systems like this. (This is what I did in my preschool classrooms, by the way. In that case, though, we had overhead shelves so that much of my manipulatives baskets and puzzles were up and had to be requested....which meant that we cleaned something else up.)
PM me if you want more details.