In a large bowl, combine the refried beans, chilies, 1 teaspoon chili powder and 1 teaspoon cumin. Spread over a 14-in. platter. In another bowl, mash the avocados; add 1/4 cup onion, lemon juice, sugar, celery salt and cayenne. Spread over the bean layer.
Combine 1 cup salsa, sour cream, mayonnaise, paprika, garlic powder, pepper sauce, oregano and remaining onion, cumin and chili powder. Spread over avocado layer; sprinkle with Monterey Jack and cheddar cheese.
In a large bowl, beat the cream cheese until smooth. Add the remaining salsa. Spread over cheeses. Sprinkle with the green onions and tomatoes. Cover and refrigerate until serving. Serve with chips or vegetables.