The best part about going to a hybrid setup is that you can allow voltage drop across your SMPS output filter while still staying above the dropout voltage of your linear regulator. This makes it possible to use multi-stage RC filters or an active capacitance multiplier circuit without compromising the load regulation.
Unless you have a very tight power budget I would go a bit higher than 16 V. Make a +20 SMPS output for a 15 volt supply. Now you can put a 1 uF capacitor, a 20 ohm series resistor, and another 1 uF capacitor before your linear regulator. At 100 mA current load you now have 18 V input to your linear regulator (In this case you can use a standard, rather than LDO regulator). Or, if you prefer, drop the switch mode supply down to +18 V and use an LDO.
A capacitance multiplier looks a lot like a standard voltage regulator, but it lacks a reference voltage -- it tracks the input at low frequency. However, they can have excellent ripple rejection at high frequency, much better than a standard linear regulator. It only takes 4 components: an NPN transistor, two resistors, and a capacitor.