Tadasana, or Mountain Pose, is one of my favorites. It makes me feel connected to the Earth, like my roots go all the way down to the core, past the Tree of Knowledge, to the molten part. It's as though the molten part of me unites with the molten core of Gaia.
I like to hold Tadasana with my hands in Prayer Pose. A recent teacher encouraged me to hold it 3-5 minutes. I like to hold it even longer, as a standing meditation.