I'm not a fan of Great Falls, but there are two things (not counting people) that I like:
1) Rikki's for pizza and salad
2) The singletrack trail from Rainbow Dam to Cochrane Dam and beyond.
The trail used to be good, but after my Sunday morning run, I now think it's pretty great. The trail parallels the paved South portion of the River's Edge Trail for about a half mile then takes off on its own. After Whitmore Ravine, you climb up a bit until the trail skims along the southern shore of the river. In the past, this part of the trail would eventually only lead back to a prairie trail for the rest of the journey to Cochrane Dam. This year, though, they extended the portion along the river. Some parts are still flagged, but it looks like it will go all the way to the dam. The exciting part is that it's fun singletrack. It's not flat, but rolling, with steep areas (steep enough that people were walking or carrying their bikes). Its got rocky sections, places you could drop right off down into the river if you aren't paying attention, great scenery, and some shelter from the wind. Round trip from Rainbow to Cochrane Dam would be around 7-8 miles, but you can also continue on to Box Elder Creek.
Now, if only we could get back on the trail SW of town that BNSF has made all ugly due to the posted white signs threatening to fine those of us seeking nature!