Good answer!
For the trails, head out north of Stanley to Cape Horn, Boundary Creek, and you can even go on through Bear Valley, Deadwood, Warm Lake and on to Cascade/McCall if you wanted to. Trails south of town head out toward Obsidian and Smiley Creek. Pretty cool to be along the Sawtooth Front, but if you headed out to the play areas near Smiley Creek and the Headwaters of the Salmon River, it is usually best to load up and trailer to one of the pulloffs near Smiley Creek.
You can find meadows and rolling hills pretty much everywhere. Just be careful on some of the meadows have pretty substantial creeks running through that are hard to see until you are right on top of them.
For the steep and deep, there is two main areas: Headwaters (which include the main Salmon, Frenchman's Creek and Smiley Creek) and the White Clouds (best access is up Pole Creek or 4th of July).
Stop into Williams Motorsports or up at Smiley Creek Lodge and they usually have maps and can point you to the right locations.
Have fun and report on your trip when you get back. We like pictures.
I'll do the same for my trip up in the Clayton area. Hopefully I can get up there next weekend.