I've been there many years ago, but I actually don't know about famous places. I just found this site. http://www.osaka-info.jp/en/
Osaka Castle, Osaka Aquarium Kaiyukan, Shinsekai etc are famous, and I think you should go to Dotombori. There're many restaurants.
Also, there's America mura in Shinsaibashi, and there were some record shops around there before, and the King Kong Records are still there. http://www.kingkong-music.com/index.php?main_page=page_3
I've stumbled upon this site many times in my Google searches for hard to find records. What's the story? Is it good, legit, etc.? Does anyone recommend any alternatives?