Choosing a conference where one will give a talk has become more fraught than ever. Nowadays, we are lucky if our university pays for one or two conferences per academic year. Often, academics have to shoulder out-of-pocket expenses to attend conferences. This is why I believe that the choice of where you will give your talk should be approached carefully.
Many young academics choose to speak at conferences that are dedicated to their research interests. I think this is a mistake. You don't want to end up with a CV showing that you kept doing the same thing for years. Nowadays, only a very broad range of research interests and teaching experiences will guarantee a comfortable career path for an academic in the Humanities.
When I choose a conference, I always select a panel that will discuss something I have never addressed, studied, or even considered before. In May, I gave a talk on the Spanish mystery novel. Next week, I will be speaking about the horror genre. It was weary work to get myself knowledgeable enough about these subjects since they lie so far away from my regular research interests (identity, ideology, female Bildungsroman, XIXth century Realism.) However, once I got over my initial resistance to these topics, I have discovered a very interesting tendency that the mystery novels and the horror novels share in contemporary Spanish literature. As a result, I will be able to combine the two conference talks into an article ready for publication with very little extra work.
Sometimes, you get so comfortable with your primary area of interest that it's hard to push yourself to explore other research interests. There are people who keep giving talks on the subject of their doctoral dissertation years after they got their PhD. I never wanted to turn into this sad staple of academic life, whose appearance at a conference is greeted by a fatigued sigh of "Here she goes again with her Bildungsroman obsession." Yesterday, I talked with an older colleague who is a very respected and productive scholar, and he told me that choosing a subject he has never worked on before for a conference talk has been his life-long - and very successful! - strategy.
I understand that this advice will not be useful to people in the sciences because the purpose of going to conferences is different from what it is for people in the Humanities. For my colleagues in the Humanities, though, this should be something to think about.