The Fate Bell Pictograph Site tour is a ranger led tour that is given at 10am and 3pm. The cost is $5. You start the tour by hiking downhill from the Visitor's Center down into Seminole Canyon and then over to the Fate Bell rock shelter. There you can see numerous, impressive pictographs made from ancient native American settlers from the past. Many of the pictographs are visible, but sadly they are fading quickly over time. It is believed that when the nearby Amistad Reservoir was created in the 1960's, the increase in relative humidity in the air is causing the pictographs to fade away.
In my opinion, this is $5 well spent. I would encourage you to see the pictographs while you can.
The Windmill Nature Trail is a short, basic nature trail that loops along the canyon and ends near the windmill near the Visitor's Center. There are exhibit signs identifying various plants along the way, but the trail isn't very impressive in my opinion.