1.2V, 2.5V and 3.3V from 5V
You can generate all three rails (3.3, 2.5 and 1.2) from a single chip, the Alegro A4490: Triple Output Step-Down Switching Regulator.  It is available from Digi-Key in a 20-VQFN package.

I have used this chip in several projects, and it works fine.  You can run at least 2A through each output.