There are more than 450 shochu distiller and more than 5000 labels of shochu!
I think Korean Soju is more common in the us. Most common label is Jinro. Soju is made almost the same way as Shochu but to me they taste very different. I thinks Shochu is more clean and delicate.
Many restaurants in Japan offer Shochu by bottles. When you order a bottle of Shochu, you'll also get all the accondiments such as ice bucket, lemon, water, tea etc. When you cannot finish the bottle at once, you can put your name on it and the restaurant will keep it for you untill your next visit.
Restaurant who serves Shochu by bottle in San Francisco:
Sakana, 605 Post Street