Air-and-hotel packages can sometimes offer savings over à la carte pricing. As a quick test, I compared an August weekend trip between London and Ljubljana, Slovenia, with two nights at the four-star Grand Union Hotel Garni.
The package price came out to £288 (about $580 U.S. dollars; see XE.com for current exchange rates) per person, while the price for booking the same flight and room type individually was £341. I doubt the price difference is that extreme in most cases, but it is a compelling reason to at least add easyJetHolidays.com to a search.
Since packages include round-trip airfare, they will be most useful for North Americans who want to use one European city as a base but still visit others. It could also be useful if most of your travels are within one region (for instance, Western Europe), but you want to include a more distant city (say, Riga, Latvia) in your itinerary.