Heat oven to 350°F; line sheets with parchment to prevent sticking.
Beat peanut butter, both sugars, and butter in very large bowl about 2 minutes until creamy and combined.
Beat in eggs individually, mixing well after each; add vanilla.
Separately stir oats, baking soda, and salt; mix thoroughly into peanut butter mixture.
Fold in chips and M&Ms, reserving handful of each for tops.
Use 2-tablespoon scoop or roll golf-ball-size portions; place 3 inches apart to allow spreading.
Gently press reserved chips and M&Ms into tops.
Bake 13-15 minutes until edges golden and centers slightly underdone; they keep cooking on pan.
Cool on sheet 5 minutes; transfer to rack. Best slightly warm with melty chocolate.