1. Harney Peak. At 7,242 feet, it's the highest point east of the Rockies and west of the Pyrenees. Make sure you go on a nice, clear day - the views will take your breath away. With a round-trip of about six miles, it's not a difficult hike, but you do want to be aware that you have to climb over one little mountain in order to get to Harney...so on the way back, there's some uphill work to do! People often forget about that. Find the trailhead at Sylvan Lake. Go early, before it gets hot.
2. Bear Butte. It's located by Sturgis and gives you a view of four states on a clear day. Hiker beware: it's a difficult, rocky trail with lots of steps and, thanks to the fire that burned there some years ago, no shade. We hiked on a hot, hot day, and that took a lot of the enjoyment right out of it. But when you get to the top...wow. Take care not to disturb the prayer clothes left by the Native Americans.
3. M Hill. Located right there in Rapid City - you don't even have to leave town! Find the trailhead across the creek by the Abourezk law firm. It's a fairly easy hike, but it's secluded - we only saw one biker (BIKE it? are you CRAZY?) and we had the M all to ourselves as we sat and watched the busy street below.
4. Skyline Drive. You can follow the road or trek off through the many trails in the woods. Come to the top by the communications towers or Dinosaur Hill! On the way back down, trudge through the woods and see the amazing examples of petrified wood. This is an easy, short hike, and you'll have to share the road with some speeding cars, and you'll probably have to share the lookout points with horny teenagers, but watching the sunset from up there is a lovely experience, indeed.
5. Old Baldy. Near Deadwood, it's a fairly easy hike with mediocre views of the prairie and hills. So why did it make the top five? I was keeping phenomenal company the entire way up and back, we had a delightful picnic at the summit, the weather was lovely, and someone else carried my water. It just goes to show, it doesn't matter so much where you go - just so you're with people you really enjoy.