The Bay Loop trail is a multi-use single track that is used by bikers, runners, and hikers, each often times with their canine companions. It's pretty much flat, almost always within a stone's throw of Chickamauga Lake, and consequently with a lot of nice lake views. http://tnstateparks.com/parks/activities/harrison-bay-hiking
A favorite of ours for waterfalls and views. A fairly easy hike is just to go up to the base of Laurel Falls. Good in winter and spring when the water flow is stronger. Going on up to the overlooks above requires more climbing, especially a rugged steep scramble through a notch in the bluff to get up on top; but the views from Laurel Creek and Bryan overlooks are worth it. For a longer more strenuous option we continue on upstream and cross over to climb the other side of the gorge. There we go to Snow Falls or Buzzard Point Overlook (another great view), or we do both. Reaching Snow Falls requires wading the creek just before you get to the falls, so that's not such a good option in colder weather.
(Note: As of October 2015 the first metal bridge, the one over Laurel Creek, is blocked by a large tree that fell along most of the length of the bridge. Rock stepping across the creek just downstream is possible but tricky.) http://cumberlandtrail.org/website/maps-and-guides/trail-segments/laurel-snow/laurel-snow-sna-section/
Spring City Piney River
A big favorite in spring for wildflowers. Sometimes we hike up to Logging Camp campsite and back; sometimes we hike down from Newby Branch trailhead to Spider Den Bluff and back; and sometimes we hike all the way through with a car shuttle. Usually we do the through-hikes uphill because the views of the water seem better that way, and the climb is not really that bad. The main point of concern is the crossing of McDonald Branch; you have to step on large rocks and boulders that can be quite slippery when wet. Also, we've pretty much given up on starting from Walden Mtn Road at the Duskin Creek parking area because the road is so very rough and not often maintained. http://cumberlandtrail.org/website/maps-and-guides/trail-segments/piney-river/
A nice late spring wildflower hike, especially for pink and yellow Lady Slippers. A pretty good climb (we don't drive to the top, even though you can!), there are some great views to the east up on top.