My advice: Make sure they know how interested you are in them in particular. I think I missed getting some jobs by failing to make this clear. Firms yield-protect. They won't hire you if they suspect you'll take another job if offered. If fact, you might come right out and say, "I want you to know that I'd rather work for you than for any other firm because..." I'm about 90% convinced that a line like that would have secured me a job this past interview season, but I didn't say it and was passed up because it didn't look like they were my first choice.