Start by making a list of the benefits of your product--i.e. the reasons your target audience should buy it. If your hotel has a pool and on-site babysitting service, sell the fact that families can keep cool together and parents can enjoy some alone time when they're ready.
Once you have the benefits down pat, you can craft a headline that stops a consumer in their tracks. After the headline, remind them of the "pain" that stems from not having the product or service--for example, wasting time while on vacation trying to find activities for the kids--and then the "solution" that you can provide. Follow up by telling the consumer how to take "action" and you've managed to craft a quick, effective ad.