2x4 and 2x6 are readily available in grades ranging from Construction Common to Clear All Heart with many grades in between. 2x8, 2x10 and 2x12 are available for skirting on the deck, and 2x2 is readily availble to make a beautiful Redwood Railing. It is important to take into account, the look you desire , the budget you have, and the area the deck will be built, in order to determine the best size and grade suitable for your use!