It depends on the look you're going for. Stacking the tile gives a contemporary look, while an offset pattern (what you term staggered) is more traditional. In either case a contrasting grout, whether lighter or darker than the tile accentuates the pattern, and a grout that matches the tile is more subdued and gives a more blended look. So it's really up to you to figure out the look you want and then select the pattern and grout color to achieve it.