Honestly, I think the entire rating system should be remade. A lot of people, including myself, didn't like when YouTube trashed the 5 star rating system and switched over to a simple, "Like/Dislike" system but the plain and simple truth is 90% of people either voted 1 star or 5 stars depending on whether they liked the video or not. Very few people ever honestly analyzed the video in comparison to some of their favorites and gave it a proper rating.
I think the same goes for maps. People either like them or don't. The best maps will still stand out because they'll have more ratings than all the others.
As for trying to find a spotlight-worthy map each week, admins could see which have the most likes and and downloads and try out the maps accordingly.
I think the problem here is not enough people are voting. I feel like the solution to this is to turn the website into a slightly more social network kind of site without going overboard. A simple site bar like the one Google + or Facebook use could be used to notify you more easily of new messages (which are currently easy to overlook) and could also have a drop-down for "Rating Pending" maps that have been previously downloaded. If you didn't like the map enough but don't think its worthy of a negative vote, you can simply skip rating it by clearing it from the pending list. The point is I think that most users would be more engaged with the website with a bar that displays important things. Notifications are the kind of thing people can't help but check. As long as Rating Pending notifications aren't obtrusive color they shouldn't be annoying either.
I understand this isn't going to be easy to implement but I think it would really help out the community.
Also, we can make a section that is updated automatically with maps that "Still Need to be Rated" that consist of maps that have been downloaded a certain amount of times but have yet to be rated or have very few ratings.
For example, 10 downloads 1 rating probably wouldn't show up but something like 50 downloads 3 ratings would.
Just some ideas.