I'm planning a trip in early January. First-timers. Prebooking most of our tours. Should we do a 2 day trip to Halong Bay or a 1 day trip to Halong Bay and then a 1 day trip to Tam Coc? I know this will not be 'relaxing' but i want to fit the most in and see the most on my 13 day trip to Vietnam. Being winter, kayaking and swimming are out in halong bay. Is a 2 day trip to halong bay still worthwhile in winter? or is it worth seeing 2 different things rather than spending more time in one?