Laurel Falls is an easy hike, I usually hike that the first day I'm in the Smokies, just to get my trail legs back.
For hiking and fishing, Chimney Tops is a good trail. Good fishing at the beginning of the trail and a beautiful view from the top. It's moderately difficult, but short, I think 4 or 5 miles round trip. Abram's Falls in Cades Cove is another fish/hike trail. The stream runs along side the trail the entire way except for one or two spots, 10 miles round trip.
If you want to do a serious hike while you're there, look to Ramsey's Cascades or Mt. LeConte. Both are 10-12 miles and are demanding hikes, but well worth it.