Last night, Amor Towles drew another rousing bookstore crowd, this time at Vero Beach Book Center, Vero Beach, Fla. In the six months since publication of Towles's A Gentleman in Moscow (Viking), he has visited 50 bookstores in 22 states and will continue on tour through the summer. The book keeps growing in popularity: sales are up to 300,000 copies, weekly sales for A Gentleman in Moscow are higher than they were in September, and the book remains on the New York Times bestseller list. As a result of all this good news, the publisher is delaying the paperback edition indefinitely.