Research is definitely important for what are considered the most prestigious medical schools, though it need not be lab work (clinical research, economics, health services, anthropology, are all just as good to name a few). However, you are correct in wondering about whether doing research at an outside institution as opposed to your home institution is a good idea. You can usually get more meaningful experiences out of doing research at home, such as abstracts, papers, or a thesis, whereas it is very difficult to get something like that out of a 2 month stay at a hospital or lab across the country. Also, ADCOMs do not care about how "prestigious" your research experience is, they care about what you learned from it and if you are one of the hardworking/lucky few who can get an abstract or paper out of it, they are VERY impressed by that. So the frenzy about getting into an official Harvard or Hopkins structured research program in particular may not be justified.