I've got a couple of things that I'd like to talk about a little bit with regard to submitting stories/posts.
First, I think moving the "Choose a Topic" to the top of the form makes a lot of sense - I nearly always end up finding it 2/3 of the way down the screen and entering it first, since it directly affects the rest of my workflow when filling out a post submission (ie. customizable title dependency on moderator setting for a given topic, etc.). Having it first makes a lot more sense and would smooth out a minor annoyance, I think.
Second, and this might be a larger discussion, but I find that the posts I'd most like to submit would be a combination of link/text - a link that sparked something with me, and some commentary on why I think it's interesting/important. I've tried to work around this by creating a link post and adding an early comment with commentary, but it's not quite the same. It feels like we could create a better engagement and quality level of link (or image/video) posts if there was a better mechanism for including commentary about the link being submitted.
I'd also like to be able to submit multiple links (with commentary on each) to create a cohesive "topic" post about an event - something that's newsworthy like the recent discovery of gravitational wave existence could make a cool deeper dive/post in +Science.
Looking forward to feedback, and I'm fully aware you guys probably have a lot of adjustments on the roadmap, so I'm just getting my 2 cents in. :)