Holy coincidence, Batman! I just contracted to have the two large trees in my back yard removed.
I wanted to get rid of the Sweet Gum simply because I am tired of the spiked ball seed pods it drops. The other a Honey Locust (Thornless) is "near the end of it life span." I could have the dead portions cut out, and the canopy raised/trimmed -- it would probably last another 5 years, possibly more. But I figure it makes more sense to remove both at the same time and put in new trees.
My current plan is to never move, so I don't mind that it might be a few years before I have good shade again. The issue is finding a balance between getting shade I can enjoy during my lifetime and getting a tree I won't have to remove in 40 years, assuming I'm still alive and living there (both of which are hopefully, likely).
Top of the list for replacement selection currently are Frontier Elm, Swamp White Oak, and Yellow Birch. Also considering an "ornamental" tree near the back porch...
“Extinction is the rule. Survival is the exception.” -- Carl Sagan