Bigger is nice, but I'm going to give you one other thing to think about...are you going to install HVAC? If you are, the cost goes up dramatically for a bigger space. Now, if you can swing having a big shop that also has HVAC, you will have the best of both worlds.
I installed a window air conditioning/heat unit in the shop I built in my back yard, and was glad I did. For reference, the shop was about 20'x25' with insulation and sheet rock. It worked just fine, but I had to get creative moving things around at times. Having a comfortable space to work that's always at the right temperature is conducive to going out there and getting an hour or two of work done even when you only have a little bit of time. And that helps keep the momentum going. Here in southeast Texas, the heat is a bigger concern, but in Kansas, I'm guessing the winters are the bigger issue. So think about how you're going to keep your fingers from sticking to tools on those cold days. You may be young and tolerant, but you can be the judge of what you can tolerate.
And yes, absolutely install lots of lighting. Maybe even more than you think you'll need. A fellow pilot/builder who was also an electrician advised me to install tons of lights--and he was right. Think about where your workbenches are going to be; especially things like drill presses. It's inconvenient to move around light stands every time you work on something. I've worked in shops with minimal lighting, and it's not as nice as having a well-lit shop.