When you're talking marriage you want your proposal to be exciting and fun. Personalize it as much as possible and tailor it to what your bride-to-be loves to do. If she enjoys the outdoors you could go on an all-day hiking excursion and then propose at the top of the mountain. A boat ride is another option. You could work with the scoreboard operators and propose at a baseball or basketball game but make sure you'll get a positive response or you could have some serious egg on your face! Yes, it has been known to happen.
On the other hand, business proposals are typically more analytical in nature. Statistics can be a key in making your case. Lay out both the pro's and con's of the plan. Keep the attention of your audience with video, audio, graphs, and charts in a variety of colors as appropriate. You won't win them over if they're falling asleep in the middle of your presentation.