I will be going to Thailand the beginning of March 2014, then Laos in April, and Cambodia in May. I have talked with a doctor and I will be getting my vaccinations that are needed for the trip. She said she recommends it but its not required to take malaria medicine. I'm not sure the exact whereabouts I will be in these countries but of course I want to be prepared. Some people have said its not something you will need if you stay more in the touristy areas. Advice?
There is no one size fits all answer to your question. Assessing risk depends where you going, when you are going and what your planned activities are.
Even within a country the risk for malaria is variable. In general, urban areas are zero to low risk and rural areas beside the rain forest are much higher risk. So if you are going on an extended jungle trek in a high risk area than you will need prophylaxis.
March and April are among the driest months in South-East Asia and that lowers the risk somewhat. May is a little wetter but is still not yet the full-blown monsoon.
You can also consider "standby emergency treatment of malaria" instead of prophylaxis provided you have the appropriate risk profile.