I'd say they actually have fine visual hierarchy, they are visually on the top level of the map (although they may be competing with the freeway a bit). I think the real issue is, are they easily decodable? For faster reference you might try pictographic symbols instead of plain symbols. Use symbols that display the activity itself instead of making the map reader remember what the letters mean or go back to a legend to decode.
On the map itself, knowing that you have a lot more work to do I won't go to far into what needs to be done but I will mention two issues that jump out at me:
1) Road hierarchy. all your surface streets go over the orange Hwy. lines. I suspect this is not actually the case but don't know. Whether they go over or under they should probably all be broken by a bridge tic symbol, right now they look like "at grade" crossings.
2) The shadow. I think your trying to highlight the city boundaries but it has an odd effect since many of the map features cross from background onto the raised city area. I think you could get away with it if you choose to show only what was inside the city limit (which would create an island effect) or if you grayed and muted the map details outside the city limit so that roads and rivers would go from muted to color at the boundary line.
I like the color choices so far, good palette. Keep us posted on your progress.
Thanks for your input. I made an attempt at pictographics, but the size and quality caused a problem, so I went with circles.
As for the roads crossing the interstates, I have not worked on this yet as most do not go over the interstate. I have been playing with different ideas for a background shadow and will probably not use one. However, I do like your idea on this.
As I mentioned, I am a long ways from complete and was having some concerns with the sporting event locations not standing out, so I thought I would do a quick post.