Hello Dominic
I experienced the sensation of ‘legs trembling’ at Callanish which was down to the fact it was very cold with a biting wind and my coat wasn’t warm enough. Had the same experience at Avebury once or twice and other stone circles too when I’ve been cold, wet or hungry. I imagine your question is not about being cold and wet though.
I’ve been to Boscawen-un where I did experience a sense of euphoria, no trembling involved, which was down to several factors - the achievement of finding my way there by foot, the bright elemental weather of a sunny April afternoon, the pale moon overhead in daylight. I’ve also had similar experiences at other stone circles such as the Ring of Brodgar and Castlerigg - in all cases there has been sunlight, a warm wind, and a walk involved.
Probably not much help but good luck with your project.