I'll start my trails review with Uvas Canyon in Santa Clara County (Morgan Hill, CA). Because it was the one, we hiked today. The park is relatively small (about 6 miles of hiking trails), and is perfect for family hikes with small kids. The most popular is Waterfall loop trail of about a mile, where you can see multiple waterfalls. The trail is following the creek, so it is not very hot at any weather. Picnic tables for day use and overnight camp sites are available. Day use parking fee is $6. Dogs allowed, alcohol prohibited.

A trail that is challenging and is nothing but a steady incline is Barr Trail going up Pikes Peak in Manitou Springs, CO (Colorado Springs, CO).  I found it a fun and enjoyable hike, however the last two miles at the top of of the trail (Pikes Peak) are tuff.  I laugh everytime I think about my hike up the mountain, becasue while I was hiking up a few people were running up it.  As I learned they were training for the Pikes Peak Marathon, so I would put them in the professional catagory.

Three favorites: Signal Ridge Trail, Desolation Trail, and the Sawyer River Trail.. all along the sides of Mt. Carrigain in Grafton Co., NH. Easy to get to, varying degrees of difficulty, and spectacular views (especially of Mt. Lowell) when you get to the top.