My father built a little perch/platform for my boys to look out my bedroom window to the front yard and street. The window is only a foot from the floor, but Teddy was spending almost 2 hours each morning standing on his tippy toes to watch all of the activity out front. The perch is probably more like the first one you built. We call it "the reviewing stand."
For your new one to accommodate your higher windows and still be safe for your pup, you will probably need stairs. Is your new pup a jumper or climber? You might have to incorporate something into the design to prevent jumping...something like a mini-pup deck for the window.
Looking forward to seeing other people's designs.