This depends entirely on your purpose in taking the photos. It used to be that most publications wanted only slides. This is slowly changing - check with whatever publications you have in mind. More importantly, understand that it will be quite expensive to convert slides to prints so there will be a considerable financial barrier to making blowups of all those fantastic shots you took and hanging them on your walls. Keep your lens clean.
Many experienced photographers take multiple lenses .
You can't take shots with a camera you've left in your hotel. Every time you change your lens you expose the inside of your camera to dust and dirt. Many great shots have been missed because the photographer was busy screwing on just the right lens. I cannot remember more than a handful of times when I really felt the need for a lens I didn't have, and then I probably wouldn't have had time to put it on my camera. Carrying multiple bodies was out of the question.