We had 4 great days. 3 days biking and 1 1/2 day at Halong Bay on cruise. Well structured program. Mostly great rides except one day with a boring route. We travelled with 3 kids so maybe options were limited first day. The guide was great, nice and flexible. We biked through green landscape and beauty. We rolled through small villages and stopped at intersting sights. We had simple and great local food. Biking is the unique and best vehicle to explore as the speed is perfect and you get to places you otherwise wouldn't. And you get hungry and thirsty. And fit.
Halong Bay was a positive surprise. Not very crowded and great hospitality at the boat. Really relaxing and perfect in between the bike rides.