I'm like you. I have a unit the cools the downstairs fine, but am supplementing the top with window units.
I can take this to another thread, but I am considering 2 a/c units for the top and bottom floors. This would require reduct work, which is high$$$. OR I can do a ductless unit upstairs. I want to say that a ductless unit would be $5K. And reduct work would be around $20K, with the 2 units and new furnace.
My main a/c unit is very old and requires new freeon every 2-3 years. So that will go when I do an upgrade. Any thoughts?