I have nothing against Kansas, and I've been through it several times, ridden through it, hunted pheasants many seasons. Kansas has many attributes, and beauty can be found in all of God's creation. However, I can say, I would not make Kansas a destination, unless there was some other motiviation. One thing about it, you can set the cruise and not make a turn for many miles. Kansas is flat, that's for sure. I saw something once where some university studied whether a pancake or Kansas was flatter. Once you blow the pancake up to the same size, Kansas WAS flatter than a pancake!
If you want to ride through some beautiful country, try AR-kansas. Eastern Tennessee is also beautiful.
If you must go to Kansas, I'd probably say fall, September perhaps. That would keep you out of the Summer heat, and Spring/Summer storms. Kansas can be pretty unforgiving from a heat and wind standpoint. There is a reason that many of the trees are leaning toward the east. That's because of steady, strong winds.