You didn't say what you will be traveling in, so let's assume you have a motorized RV of some sort. Keep in mind that a hair dryer uses a lot of power which, if you use an inverter, means a lot of batteries. Obviously 2000 is better than 1500, and the cost difference isn't significant, so why not just get the 2000 and be done with it? In general, a 1500 watt can supply 12.5 amps, and a 2000 can supply 16.6 amps max at 120v. If it is really important to decide between the two, calculate your amp draw, including the hair dryer and make you choice based on the result.