Transfer Calculations
  Hohman Transfer
  Free Return Trajectory
  Spiral
  Summary of Numerical Data

Launch Windows
  Calculations
  Possible Launch Dates
  Graphical Comparison

Sources

Comparison of Hohman and Free Return Transfer 

Transfer	Hohman	Free Return
Delta V at Earth	6.6 km/s	11.6 km/s
Delta V at Mars	7.2 km/s	27.6 km/s
Total Delta V	13.8 km/s	39.2 km/s
Time to Mars	259 days	215 days
Time on Mars	455 days	388 days

In both cases, a Hohman Transfer return would be used.