I prefer to do flat, incline,
decline bench press myself. I really feel like it totally hits the chest from all directions.
If you are doing dips, then you don't need to do the decline press.
Some will tell you that you only need to do the flat then grab some dumbells and do press on a very
slight incline. If that works for you, then great. If you have a chest like mine - very slow to progress, then it likely needs the extra stimulation.
For many people the decline bench press is a big growth stimulator, but it targets the lower part of the chest more than the entire chest. This is why the decline is reccomended to be done last in your workout - once the rest of the chest has already been worked. This keeps the weight up on the flat and incline and down on the decline. Don't want to end up with an unbalanced, funny looking chest.
Dumbells are supposed to really be terrific for chest work, I only use a bar myself though because of an accident once with a dumbell that ended up dropped on my chest breaking two ribs.