I think toys should generally be stored where the kids can see them and play with them. In our family room where spend 80% of our time, I have 2 big baskets of toys and 1 basket of books, and those are the ones the kids play with most. We have a few larger trucks hanging around as well. The best part about open toy storage is that the kids can pick up themselves...theoretically. But even if I have to pick up the toys, it takes less than a minute to toss them in the baskets.
I have some open shelving in our basement play area where I store trucks, clear boxes of toys organized by type (balls, cars, Legos, Lincoln Logs, etc. and a few baskets of miscellaneous toys. If you use plastic boxes, use the type with clear lids so the kids can easily see inside. It's also great to rotate the toys that are in closed cabinetry to the open spaces - the toys seem new again!