Solving circuit with voltage and current sources in series
The systematic way to solve these kind of problems is nodal analysis (on which computer simulation programs are based ). http://en.wikipedia.org/wiki/Nodal_analysis

For each node you write down the equation that the sum of currents is zero. The voltages (with respect to a choosen ground) are the unknowns.

Note that the voltage sources need to be converted to current sources. If that is not possible (as in your case), the voltage between two nodes is known and one voltage can be eliminated.

In any case this will give you an equation system for the voltages, which can be solved. So this solves the circuit in more or less one step without superposition. 
It is also a systematic way, which requires (once understood) no thinking at all (well, correct calculation though).