Like Amy S. I'm a big fan of Sue. She has helped me book several trips over the years - Christmas in Hawaii, cruise to Alaska, volcanoes in Costa Rica. Most recently, she went to bat for us to arrange a trip to Argentina. She's never been there but did her homework to figure out the best options and has a wonderful resource for booking packages throughout Latin America.
Sue also knows that I don't like to have every minute scheduled. She is very good about recommending a mix of those don't-miss attractions and still letting me have a good amount of time to explore on my own.
And, she doesn't quite until the job is done. More than once she's had to call me after the office has closed to fill in some piece of info I managed to leave off my registration form.
You can do a lot of research and booking on your own. But when it comes to a new adventure in a country I've never visited before, it's nice to have someone like Sue in your corner.