At my house in Maryland Zone 7, dogwoods do much better growing under taller trees. Don't like full sun at all. I don't have any experience with the others.

I say go for it..I did..no regrets..

I am seriously considering adding a bunch more trees as well. I only wish my property looked like @nicholsworth Z6 Indianapolis's! I don't have enough knowledge to talk you out of any specific trees, but I support the idea of adding a lot more trees to your property! Great for the environment, great for bird and animal habitat, great for making a yard more enjoyable. What's not to love.

I say go for it too!! I planted 6 trees in a smallish suburban back garden maybe 20 years ago that was already populated by a ginormous 80'+ Douglas fir. They are all still doing just fine the last time I drove past that property.

I don't think you can have too many trees :-)