Grid Based 2D Game

Hi,
I am thinking of making a grid based 2D game (some examples are chess, minesweeper or the classic turn the pipe game - http://www.funnygames.in/game/plumber.html).
I am a little confused on the way to approach the game:
1. Should I make the game in the canvas using a grid layout group? This would help in the case of supporting multiple aspect ratios (or I think it will)
OR
2 Should I use sprite render to render the sprite and manually manage the layout?

In either of the approaches I have some doubts:
In approach 1, when I use the canvas, if I set the grid layout for 4:3, I get a lot of empty space on 16:9. How do I make sure that doesn't happen and the grid actually resizes and fits the whole screen?
In the second approach, how would I handle the layout for different aspect ratios? Manually detect the screen resolution and scale objects at my end or is there something I am missing?

In both the approaches how would I handle HD and SD graphics? are mipmaps the way to go? or do I load a different set of graphics?

While making the game in cocos2d-x, we had to load 4 different sets of assets to support all possible aspect rations (not just 16:9 and 4:3).
This is my first attempt at a grid based game in unity and hence I am looking for advice on which way to go forward.