Power Supply for WiFi Module
A DC to DC converter is definitely the way to go if:
1) the cost of an LDO vs DC converter makes sense (DC converters are more)
2) the energy lost in the LDO is unacceptable  

There are ways to overcome the thermal limts of LDO's like paralleling them or dropping the voltage in stages (thus spreading the thermal heat across multiple devices)

There are drop in compatible DC to DC converters available that 'drop in' the same through hole footprint of a 78XX regulator . Generally the input and output capacitors will be need to be larger than a 7805. If you need lower ripple LC filters do a great job, I've been able to achieve a few mV's of ripple with these converters and LC filters.