Looking for a Basic Lego set with mostly large bricks
If you can get to a Lego shop, there is a Pick a Brick wall with mostly large bricks that you buy by the cupful for less per brick than you would pay in most sets.

These two sites:

http://www.brickbuildr.com/view/pab/

, and

http://wallofbricks.com/ 

show you the current(ish) contents of the Pick a Brick walls around the world, they are updated by fans so they might not be up to date.