I generally dislike stains. I would much rather use contrasting or different-colored woods. Sometimes I need the contrast, but the design of the piece requires that all the parts be cut from the same piece of wood.
I use plywood when strength or large panels are required. If I am concerned about the color of the plywood, I have made my own plywood in small quantities. The first time I did this was for a mastodon that I made for my grandson. I made the plywood from 1/16-inch thick wood. The shop-made plywood was incredibly strong. After cutting out the tusks for the mastodon, I could not break them with my hands. So far, it has survived two grandkids.
You need to consider the project at hand and its intended use. Will it sit on a shelf, hang on a wall, or will it get some hard use, like a kid's toy might?
With solid wood, it's essential to keep in mind that wood expands and contracts with changes in humidity. On small parts, this doesn't matter much, but as your project gets larger, the movement becomes more of an issue.