Exchange student from Spain, what can we do to make it a fun experience for her?

First of all, do not overwhelm her with activities, perhaps one big or two smaller activities a day is more than enough. Give her time to talk and to get to know your family. If you have pictures from your own earlier trip, try labeling them with names and captions in English.. either put together an album or just put the captions on the back of the photos. A walk or ride , window shopping etc. can be calm, interesting, and help you both get to practice your speaking skills. Also, communicate with her. what does she want to do? Does she have a special interest in something ? For example is she interested in exploring caves? try Chislehurst caves? Does she have fantasies of being a royal? Take her to Windsor castle. Does she like history, museums, shopping or what? Maybe get some of those little pamphlets about activities and events and send those to her ahead of time. You can communicate by snail mail or e mail to work out an agenda which will suit her interests. This will also encourage her to look forward to the trip. We have had more than a dozen exchange students from 3 days to a full school year. Each one is different. relax, be yourself and talk.