A good simple option mentioned by several users is Picasa/Picasa Photo Viewer on Windows. It was recommended as an easy way to browse and organize photos, and one responder said they use it on a touchscreen laptop. It can scan selected folders or your whole computer, monitor folders for new images, and provides straightforward photo browsing that may suit event viewing better than Lightroom.

Another possibility mentioned was Photoshop Elements Organizer, but the comments leaned toward Picasa as the simpler, more user-friendly choice.

If your main goal is quick guest browsing on a touch display, try a lightweight photo viewer/organizer first and test whether it clearly shows thumbnails, full-size images, and filenames in a touch-friendly layout.