I just returned from a trip to England. I'm very lucky to have friends and my husband's family there -- it provides a reason and an excuse to return frequently. But my real reason? Is to do research.
I love visiting the homes and gardens of people who lived long ago. I realize that things have changed -- sometimes entire houses are demolished and rebuilt. But just seeing the site where Anne Boleyn may have been born, or the location where Catherine Howard was held before being taken to the Tower -- gives a sense of place, of being, of setting. It helps me, personally, but I also helps my writing.
The other thing I love is getting books on my subjects that I can't purchase in the shops in America. I always leave room in my bags to bring home at least two or three books. (this time I brought back eight, if you include the site-specific photo guides to each house I visited...) Now I just need to find the time to read them!