Hi,
Vietnam Tour Booking and Halong Bay Tours sound good, but if you want to travel in Halong i think you should book cruise or tour at Halong Bay Tours because as i saw, they have more cruise than Vietnam Tour Booking.
Happy travels!
If you want to travel around Halong with 1 day, i think it is impossiable beacuse you spend 4 hrs to Halong from Hanoi. Furthermore, the best way to explore Halong is cruise which you should overnight. Vietnam Tour Booking is travel agency which i booked tour for my family last year with Halong...