Tip: When making your overworld, mix the terrain up! Add decorations to the overworld. Don't leave large empty grass or sea regions. As an example, angled land and multiple colors look much more interesting than square land and flat, plain colors.
This patch allows you to have a 128x128 image as the Nintendo Presents logo, with an optional feature to allow a custom palette to be loaded as well. Check out the asm file for more info. Included sample ExGFX and mw3 files for the image you see here.
For the most part, that patch works fine. There is only one exception: If you enable a custom palette for Nintendo Presents then Mario Start will use the same palette as Nintendo Presents. $0093CA isn't just processed by the credits but also by Mario Start. Fix that and I'll accept it.