Well, if the unlimited resources included more humans, or maybe better another habitable planet (then no mass murder would be necessary), I would completely repopulate the Earth (besides yours truly). I would try to keep the same level of technology, but let culture redevelop on its own. The change would be that races would be mixed always, rather than originating from certain regions. I think it would be interesting to see how cultural and political boundaries would change if obvious physical differences were taken out of the question. Sort of like the colonization of the New World, but hopefully with less genocide, forced conversion, established empires and mercantalist oppression.
To invert this experiment, I'd like to inhabit a planet with nothing but one race of people and see how long it took for genetic drift to produce new skin tones, eye colors, and so on. I'd also like to see if people again divided themselves along racial lines once new races started to emerge, particularly if they all started out and stayed primarily in one region of the planet.