In a bowl mix together the refried beans, half of the package of taco seasoning, the salsa, and 3 tablespoons of the sour cream.
(Reason for adding salsa/sourcream: layered dips can be too thick for dipping if you don't add something to thin them down a bit - the salsa and sour cream add both flavor and the thinning aspect, so you don't want to skip them. Also, you can add cayenne and/or ancho powder to taste. I usually add ancho because I love the smokey flavor.).
Spread the mixture into a large rectangular glass lasagna dish.
(If you used two cans of beans and not all of the dip will fit in the dish, spread the remaining on a dinner plate and you can make your *own* dip to keep at home while you take the rest to the party!).
In a separate bowl mix the rest of the sour cream with the remaining taco seasoning.
Spread the sour cream mixture on top of the refried beans.
Taking your guacamole, spread it carefully on top of the sour cream mixture. Take care not to mix the two together. (Some people swap these layers around - it's up to you - I just prefer the guac on top.).
Toss the two types of grated cheese together, then spread them on top of the guacamole.
Sprinkle with the tomatoes, olives, and green onions. Chill in refrigerator for at least an hour before serving.
You can make this recipe a day ahead and let it sit in the fridge overnight - let it come to room temperature before serving with round, restaurant-style tortilla chips. (The reason to serve it at room temp is so that when you attempt to dip your chips in they don't break!) Some folks like to serve this hot instead of cold: bake at 350 degrees F for 30 minutes, if you'd like to do that.
Notes: The above is my basic recipe. When I make it these days, I usually fiddle with it a bit, by: using 1 can of black bean refried beans instead of regular, adding ancho powder into the beans and sour cream, and adding a small can of chopped mild green chiles into the refried beans. When I'm lucky enough to bring home any of this from a party as leftovers, I fill flour tortillas with the dip and fry them up as burritos. They're wonderful both warm and cold, and taste great for lunch!