Easy Depth Management In Flash?

I've recently created a game in which the logic and programming all runs perfectly, however the graphics are lackluster. I'm currently having a hard time managing the depth of movieclips on the screen.Basically the game is tile based and each frame of the movieclip holds a different type of tile. All the tiles are 50x50 with the exception of one type of tile which is 60x60 and therein needs to overlap the tiles around it which are 50x50.In AS2 I could of set the depth manually, however I'm told (as is this is my first time dealing with depth in AS3) that I cannot do this anymore. Is there any suggestions on how I can make sure that a tile of one type is automatically set beneath tiles of another type - I've thought about simply coding a function to check this but it somehow seems inefficient (considering larger maps will have a lot of tiles, meaning hundreds of movieclips attached to the stage, each movieclip with multiple frames).