To get a better end shape there, you probably want to either have the end come to a single point like the front part, or maybe if you didn't want to do that because it's kind of flat you might want to make it come to a flat end shape initially and then put a planar cap on the end and then fillet where they connect.

For the latter one you'd want to have the long rails end without swooping downwards, more like so:


- Michael