Just to clarify what others have touched on - it sounds like you may be referring to 'tone mapping' rather than HDR. HDR photography involves taking multiple exposures (2 to 100 or more) of the same scene at varying exposures, allowing you to capture a much wider dynamic range of brightness to shadow than a single exposure is capable of - preserving highlight details while also exposing shadow details and everything in between. During the processing of those multiple exposures, which are stacked into one using HDR blending software, you can post-process them to achieve a realistic looking photo, that more closely captures what the human eye was able to discern in real life...or you can mess around with the tone curves and contrast to achieve a wilder look, that goes a bit beyond realism, or all the way to full-blown cartoon comic-book fantasy world style This look is typically achieved using the tone-mapping process, which is what software like the Topaz Adjust plugin is capable of producing even with single shots (though this wouldn't be 'real' HDR).
If you are thinking of just messing around with some of your photos after the fact by applying tone-mapped effects, the Topaz and similar programs will work well and can be fun. If you want to actually take multiple exposures while on the trip with the intention of stacking them for real HDR, then you will need some form of HDR stacking program. Then, you can decide if you want to process for realistic HDR style or more wild-and-crazy HDR style.
