Hi Cry,
I am having a DW in Los Cabos, Mexico. While a DW may seem like an easy fix, they do come with different, unique stressors. Many resorts handle tons of weddings so they pretty much know what to do, but you have to deal with quirks like long
response times (think Island time-bad if you are Type A), language/cultural barriers, and not being able to get certain food/drink or flowers. If you are flexible, then it will go off well.
They should pick a location that they love (Mexico, Hawaii, Caribbean, etc) to start and them look for resorts in the area that have wedding options. Have her check www.bestdestinationwedding.com. There is a forum for pretty much every destination you can image. There are many ideas and reviews for resorts.
Many resorts do offer packages, but definitely shop around for local vendors. Often the resorts (and even the local coordinators) inflate prices to make a profit. Same thing goes for photographers included with packages, make sure you like their
work and don't be afraid to bring your own (we are). I hired a local coordinator since we had a hard time with the one provided by the resort. She is great and has taken care of a lot of stress.
I also recommend doing a site visit before the wedding if the budget and time permits. I felt so much better after meeting people in person and seeing the resort.
Hope that helps! Good luck to your friend!