To me this is a gray area, where you can be aggressive (risky) or not.
If the trip is primarily personal, you can only deduct the directly related business expenses. If you were writing a review of the rafting company, I would deduct your rental fees and gear (not your family's) for the rafting excursion. You would not be able to deduct the travel or accommodations for the vacation as that is not directly related.
Conversely, if you plan a business trip with incidental personal travel, you need to separate out the mileage or meals that are personal in nature and not deduct them. Ie, deduct breakfast with a client, but not lunch with a friend.
There are different standards for travel outside the US as well.
IRS Publication 463 has a number of examples of what/when to deduct business travel.