I think you're on the right track. THe big Griz takes up too much room, the DW735 will do a fine job, and if things go your way, free up some cash. The sander, as you said, will handle thicknessing that the 735 can't, but that's it's job. An extreme makover wouldn't hurt. One thing leads to another and SHAZAM! you have a new shop with recessed lighting, zoned heat and cool, soft, flooring underfoot, and the walls color co-ordinated with your chisel handles. Hey, it could happen. Anyway, I think you have the right idea. When we see something as being in the way, or find we need to justify something, it's time for it to go. Get the most you can for it, and put the money to work.
Steve