I've already written about my search for Kolkata-style Kati Rolls in Mumbai; here's the map to help you find them.
And lets not forget New York. The Kati Roll Company fuelled many of my parties, while Roomali was a lunch staple. Indian Bread Company served excellent tea along with decent rolls and a was a great place to read books in. Roti Roll's unusual curry fillings filled me out a couple of times while wandering near Columbia.