I’m going to give you a link to a book I enjoyed for inspiration for hikes. I like it because it’s a great source for specific loops and what you can see on them. Also, it takes a very liberal approach to the definitions of a ‘hike’, and include Urban walks. I sort of hesitate to post this, because I’ve found most of these hikes not to be too crowded. So be kind, and keep to the trails.
https://www.amazon.com/Hikes-within-Miles-Washington-Including/dp/0897325559
Billy goat trails are nice and I believe there's a book that has a lot of good suggestions for this area in particular.
My typical stomping grounds that I usually hit after work in the evenings for the sake of going outside are nice little 2 milers at Difficult Run or Scott's Run. Neither of which are too far from the village of Great Falls. Plus you get to see water most of the time and the tree cover's nice. These are by no means challenging hikes, but the views are nice and the trails have many options/ routes.
I've also been looking to find a few new spots around the area. Do you have any particular hikes you could recommend to an avid trailblazer?