In a large zip baggie, combine the chicken and the pesto. Refrigerate for at least 4 hours.
While the chicken is marinating, prepare the rest of the salad. Place the greens in a large bowl and toss together. Add peaches, raspberries and cheese to the bowl. Cover the bowl with plastic wrap and refrigerate while you prepare the rest of the salad.
In a medium skillet, combine the sunflower seeds and sugar over medium heat. Stir often until the sugar melts and coats the sunflower seeds as they become toasted. Remove from the pan onto a paper towel to let cool.
Remove the chicken from the zip bag and grill over medium heat until done. Grill the corn at the same time, just enough to get some grill marks all around.
Slice the chicken and add to the salad. Cut the corn off the cob and add to the salad. Scatter the candied sunflower seeds on top. Drizzle the balsamic vinaigrette on top and toss (you may choose to use less vinaigrette, depending on your preference). Serve immediately.