The Congress Trail starts at the General Sherman Tree and is probably the most popular in the park. For this reason, try to get on this trail early to not only get a parking spot but also to enjoy the walk with less people on it. This 2 mile loop picks up 200 feet and passes many big sequoias that are named in some political fashion. The Senates are a nice cluster and do not miss the President at 240 feet tall.
This is a fairly easy trail, although there are a few peaks and valleys that have moderate elevation changes. It's a paved loop that runs around two miles, and includes some of the famous trees of the park. The granddaddy of course is General Sherman. There's also a tree known as The President as well as a couple of groups of trees known as The Senate and The House. It didn't seem as if too many people were interested in wandering along the path away from General Sherman, so you'll have plenty of time to be alone with your thoughts and nature. It took me a little under an hour to walk with several stops to look at the trees.