For Offset or Digital, resolution should be 300 dpi at 100% of the file size. The file should be created at 300 dpi, not changed from a lower number to 300. Digital is more forgiving than offset. The lower the resolution, the more pixelated your images will be. Remember that if you place a 300 dpi image into InDesign and enlarge it 200%, your file is now only 150 dpi.
Wide Format prefers that the resolution be above 100 dpi, but 72 dpi is still acceptable.