Do you have any idea of where your headed on the Yukon, it's a pretty big river. I use to fish the Dall River for pike and always caught them thee but it's been a few years since i've done that. There's a ton of sloughs and tributary's that will hold pike, you might want to narrow it down just a bit and I'm sure you will get some good replies.
I agree, there are pike throughout the river, and it spans the width of Alaska.
However, there are some trophy size pike in the backwaters and slow sloughs in the Yukon Flats, generally between Dalton Highway Yukon River Bridge through Circle, Beaver, and Fort Yukon if you are looking for a place to focus on.