I haven't used this in a long time, so not sure how functional it still is. So long, that being frank, quite surprised I found the bookmark, and it links to a page that still looks valid. I'd forgotten all about it, until the OP's post jogged my memory. It was a handy little tool, when it worked.

American Airlines Award Map (aa.com)

You will still have to search by date and origination airport as the default. However, you can set the max miles you want to use. The tool will return routes available within those parameters.