Most of the suggestions in this thread sounds really good, especially with updated sound effects like populated stadium and car engine. However, I am afraid that this is going to be more or less a pure import to the ManiaPlanet with only a few changes to graphics along with ManiaPlanet editor. But here is my ideas towards the perfect Stadium environment (competition-wise):
1. A fix to the worst bugs that may appear on ramstein or from dropping down on the road (landing bug). Also the rare ones where you bug in the middle of the track, or during a transition from grass to road (especially with the ramstein). I do see that there is a different opinion about the bugs, so an optimal solution would be a choice to make blocks with or without ramstein added. So in theory there would be 2 versions of each road-block, one with ramstein and one without. A practical solution to this could be solved like we today press the "bucket" icon (see image below) that allows you to select the blocks to add signs/advertisement. In the same way, you could have a similar button that easily switched between the two versions of the blocks. Other more positive bugs like grass-bug and speed-bug should not be changed of course, as it gives the game more depth in driving techniques (like powerslide).
2. Checkpoints that do not require their own blocks. Instead, an "add-on" to already excisting blocks. This would solve the cut problems in most cases. To totally seal it off we could add an option for giving numbers to the checkpoints so that they have to be driven in the correct order before entering the finish. The more and closer checkpoints you can have on a competition map, the more detailed analysis of your performance and speed after each turn you will get.
3. More variety in blocks for the editor. When I use the editor myself, I often come across loads of ideas for great transitions and new shapes for blocks. Luckily we have the TMUnlimiter to refresh the current range.
4. Spectator-mode. Where are the mysterious slide marks? A small but quite strange detail that is currently not added to TrackMania Nations Forever. I also miss updated and better variety of cameras for spectators, especially a stable cam1/cam2 option.
5. Better integration for streaming services, partner/sponsor logo's and detailed driving statistics. I don't know who is in charge of the FAST server config, but we are getting closer to something here with more advanced options for Checkpoints, player-points, etc. If you look at Starcraft 2 after a game ended, you will be able to see all statistics and details made during round which gives the possibility to reflect/examine your own performance. I think I speak for everyone when I say; The more detailed statistics, the more fun!
Other ideas giving a new refreshement to the game:
1. I saw this request in an article by fragster and thought it would be a great idea. Multiplayer-mode in the editor. A solution similar to Minecraft would be astounishing, where blocks are locked to author and can only be edited by others if permission allowed. This opens up alot of great interactions for multiple authors to share creative ideas and try it live. Imagine how powerful it would look if one could drive and the other make blocks at the same time. I don't know how hard this would be to code/script, but the idea is preposterous!