It stands to reason then that since God allowed Satan to rebel, God must have planned to use sin as a tool to further His Glory. While we may not see how that can be, it is not necessary for us to understand that in order for it to be true. God did not cause sin, He is not sinful in any way, but He can and has used sin in His creation as a tool. I'm inclined to think that no one can really understand how Holy and Righteous God is unless they have something to compare it to: Sin, which is the exact opposite of what God is. A study in contrasts, a graphic example, if you will.
For whatever reason, God has allowed, controlled, and directed sin in order to Glorify Himself, and to make known the riches of His Glory to those whom He has chosen to share it with. In this lifetime, we will probably never be able to answer why. It is certain that sin neither took Him by surprise, or caused Him a moment of consternation over its appearance. He knew it before it happened, and was in control of it, even then. As truly as God meant the sin of Joseph's brothers for Joseph's (and God's) good, the appearance of sin in God's creation was, and is, turned to God's good.
God created beings with the potential and capability of sinning, even though it wasn't initially in their nature to sin, nor was it God's desire that they sin, but sin they did, as God knew they would. Knowing that, He could turn what would be destructive into something that would ultimately benefit not only Him, but His chosen people as well. The end result is greater than if sin had never entered the world.
Again, you sound very Arminian to me.