Heat oven to 400° F. Coat a 13 x 9 x 2-inch baking dish with nonstick cooking spray. In a medium bowl combine Alfredo and marinara sauces. Soak lasagna noodles in warm water for 10 minutes. Set aside.
Spoon 1/2 cup of the sauce into bottom of prepared baking dish. Cover with 3 noodles, overlapping and alternating spinach and tomato, if using both varieties. Cover with 1 cup of the sauce; spread ricotta evenly over sauce. Cover with another 3 noodles and 1 cup sauce. Season spinach with salt and evenly distribute over sauce; scatter red pepper slices over spinach. Continue layering with 3 noodles, 1 cup sauce and mozzarella. Top with 3 remaining noodles and remaining sauce.
Cover with foil and bake at 400° F for 30 minutes. Uncover and sprinkle with Parmesan; bake, uncovered, for 15 minutes or until cheese is golden brown. Cool 15 minutes before serving.