I lived in St. Louis for 20 years. It might fill the OP’s more detailed and revised bill.
Winter was generally highs in the mid 30s lows in the mid 20s most of the time. With a couple weeks of lows in the teens and highs in the low 20s. So we got snow 4-12" at a time and within a few days it was gone again. So we had the pretty part, but we didn’t have the frozen piles of filthy gray crap along the edges of all our roads and in the corners of all our parking lots from mid December continuously through to mid April like they do further north.
Fall has pretty turning and falling leaves. The area is heavily forested where it hasn’t been cleared for farming or new suburbia. There’s plenty of older neighborhoods that are full of mature trees. The local trees aren’t big on bright reds, but there’s lots of yellows, brick reds, and tan/brown. Then they all go bare over winter.
Spring has the riot of all the trees leafing out and many blooming with flowers. Because there isn’t a deep layer of snow on everything there isn’t a distinct melting or break-up season where everywhere is nothing but mud for a month or two. It just warms up and the precip starts falling as rain, not snow.
Summer is hot and humid. But not as hot nor as humid as Dallas or Chicago. I visited both cities at least once a week year round for my whole 20 years and have a pretty solid sample size. The worst 3 weeks of August will be upper 90s & quite sticky. Much of summer will be 88-92 and a little sticky.
Each of the 4 seasons is about the same length. It’s human nature to think of spring and fall as brief transitions between extremes; hence the jokes about each being about 2 weeks long in most areas. It’s a meteorological fact that the farther north you go the longer winter is and the shorter summer is. The converse applies as you go south. St. Louis and other US cities at roughly the same latitude have a pretty even balance of summer and winter. The OP can adjust north or south from there to suit his preferences.
When I lived there I often thought the ideal would be to have a main house there, plus a cheap condo in, say, Miami & another in, say, Boulder. Spend Jan & Feb in Miami, July & August in Boulder, and the other 8 months in St. Louis. That would provide a very civilized life climate-wise for a fraction of the cost of living in Los Angeles year round. Unlike me, the OP doesn’t want to flee winter; my point here is that the shoulder seasons are long enough to really count as an extended spring and fall.
In addition to latitude, one way to have more snow with relatively less winter cold and usually less humidity is to gain altitude. Look at places like Flagstaff, Santa Fe, or anywhere in CO, UT, or WY.
Here’s a wiki the OP ought to read: Heating degree day - Wikipedia There’s more to “summer” and “winter” than just the highest highs or the lowest lows. The maps in that link, or others you can Google up will give you a good idea of how much total winterness or summerness any given place has. You’ll see it’s not quite as simple as just latitude + altitude as I implied above.
As to humidity, this Dew point - Wikipedia gives some understanding on what your looking for and why. Skip the math & read the summary on human perception.
This Köppen climate classification - Wikipedia and more particularly this Continental climate - Wikipedia is another good resource. You’re seeking a particular climate type. Once you know the correct terminology for it you can find maps that show where your preferred climate is found.