@Meghan1 Which area zone 6a are you in? some trees will grow in the west or east or south but not the others.
I’m in VA 6b (but with alkaline soil unlike most of VA) so these are my experiences related to that.
My flat wonderful is over 20 feet tall, you can walk under it, but it isn’t the greatest shade tree. However, it is my favorite tree for beauty. I would get one and plant it just because I like to look at it. If peach will grow in your area, put one in just for kicks when you put in your perfect tree.
I don’t think mulberry is particularly pretty (sorry all). Mine are much larger than @krismoriah’s, but his is much prettier. Mine leaf out late and always look a bit scraggly. It might just be the type I have but the branches are thin and just pop out everywhere. However, I have multiple mulberry trees that are 20+ feet tall, could be driven/walked under, produce fruit (most of which the birds get!), provide shade, and are not ugly - so they’re pretty good for your criteria.
I think pears grow too upright - I have some really old pear trees that are good shade, but I think you don’t want wait 40 years.
I think nothing beats an apple or crabapple for shade and IF MAINTAINED they are pretty. They get to 20 feet on the right rootstock, but that’s kind of the upper end - they can have a nice wide canopy though and you can walk under them. If you want fruit you may have to spray for CAR if it’s in your area, get a second tree as a pollinator (mostly), etc. so they might be more maintenance than you want. They aren’t super fast growing but they aren’t horribly slow either. My friend has two apples trees that are OLD and produce and they’re never sprayed and they are more like 30 feet tall - but I think that’s not so common in the places I’ve lived- just saying it can happen.
I love the red maple suggestion. In my area, sugar maple doesn’t grow as well as red maple. Red maple is very pretty, great for shade, walking under, hanging a swing on, etc and you can tap it for maple syrup. I did tap mine this year and it was good fun. It grows reasonably quickly and has a nice canopy.
Persimmon trees are pretty great too. I think they’re pretty. The bark is a really cool color. Mine grow well. I don’t ever have to spray them. The biggest I have is a little less than 20 feet tall. The variety I have isn’t my favorite taste wise, but I hear there are lots of good choices. The downside is that they do leaf out late - though they seem to have leaves than hang on longer than other things.
I also liked the suggestion of black walnut. I didn’t think of planting one since where I am they are literally weeds! They do produce edible nuts which I think taste good, but are such a pain to clean, store, and crack open that I don’t bother. They’ll easily get 20+ feet tall and become walkable under. They give good shade and grow quickly. They are reasonably pretty - bright green leaves in cascading long leaflets.
Maybe some of the people who grow nuts could suggest nut trees if that is of interest… @Fusion_power I think chimed in on some nut discussions and may have some ideas. I would be interested in hearing about other nut trees to plant for both eating and beauty purposes.
As an aside, since people were discussing climbing. My most climbable trees are the peach trees, followed by the apple/crabapple. The best for hanging swings and ninja course obstacles are the red maple, black walnut, and apple/crabapple.