If your client takes a trip to Bahamas and the main objective of that is business, they can deduct the entire cost of the trip come tax season.
The other expenses of the trip like hotels and food can also be deducted as long as the meals were spent talking about business and the hotel stay was also for business purposes.
Rules for travel to overseas locations are little different especially when your clients are thinking about sneaking in some vacation time. The trip cannot last more than a week and they cannot spend more than 25% of their time vacationing. If your clients are guilty of either of these breechings of IRS rules, they cannot deduct the trip as business expense.
Your clients can take their family along with them on business trips but none of their expenses are deductible. That doesn't mean that they cannot deduct their expenses out of their families even though they are with your client.