I definitely agree that a Golden Sun stage for Brawl should have the music from Venus Lighthouse, that track was one of the best in the game (which is really saying something... the whole game had absolutely beautiful music). For the actual stage, however, I would prefer Mars Lighthouse. Imagine this:
The battle starts on the ground, right outside the main entrance to the lighthouse. This part of the stage is flat and basic, and the edges of the stage are walk-off. We get a nice view of the lighthouse here, perhaps with some statues and some of the other art that (for me at least) helped give the lighthouses a feeling of dramatic significance. Then, on either side of the screen, an elevator comes down. Players must scramble onto either of the elevators, and after a couple of seconds, they both begin to rise. In matches of four characters, this forces players into tight quarters that should result in some really intense hand-to-hand combat. In matches of two people, one player could ride on each elevator. Both elevators should rise at the same speed, to allow for easier exchanges of projectiles during the ascent. The distance between the elevators should be large, but just small enough for bold players with a fair amount of skill to jump between the two sides (which allows for the battle situation to change rapidly in matches of 3-4 players, and may also help to encourage high-stake aerial exchanges). As the elevator starts to rise, we get a shot of the snowy landscape behind it, which soon dissolves into (and this is why I chose Mars over any of the other lighthouses) a breathtaking shot of the edge of the world, and finally, as the elevator nears the top, all we can see in the background is the void, ominous, ready to consume the entire world. Finally, the elevator reaches the top, and we get an awesome shot of the massive magical orb at the very top of the lighthouse (even though it's only a background object), depicted in the beautiful graphics of SSBB. For the next minute or so, the elevators remain in place, slightly separated from the main battle platform, creating a fairly wide arena consisting of three platforms. Then, finally, the elevators drop away (but you do not want to ride them this time), leaving you permanently at the top of the central platform at the top of the lighthouse. I imagine that the central platform would be roughly the size of Final Destination. So by the end, it would basically be an FD battle: wide, flat ground, and no gimmicks. Except this time, there is an even more powerful background, thanks to the orb and the void, all set to the incredible music from Venus Lighthouse.
Actually, I think the void was really called "the rift," but it's been so long since I've played GS that I can't really remember. But that's not of major significance right now. So what do you guys think?