Among the largest of more than a dozen towns and villages along the shores of scenic Lake Atitlan, Panajachel, often referred to simply as Pana, is best known as the tourist hub for the lake region. From the center of town, there are frequent buses and shuttles to outside cities like Solala, Antigua and Guatemala City. And there are plenty of boats whose pilots are eager to transport you to any of the other locations on the lake's shore. But Pana has plenty to offer in its own right, and is full of hotels and hostels, bars, cafes, restaurants, and marketplaces where the natives ply their handicrafts and sell their wares. It also boasts a couple of fine supermarkets and many ATMs, which are services not readily available in all lake locations. The address listed is for Casa Cakchiquel, a historic hotel that has hosted Ingrid Bergman, Che Guevara, and many other historical figures, and is now home to an art gallery.
If you go:
If you go anywhere near the waterfront, you'll be approached by more than one person offering you passage on a water taxi that he or she works for. As a foreigner, you'll be charged more than the locals pay, but you might be able to negotiate a little, particularly if you have more than one person seeking your business. But even at inflated rates, the fare is quite reasonable. These boats operate frequently, from early in the morning until well into the evening, so it's quite easy to get around. Within town, as within the other towns, the preferred transport is the tuk-tuk, which is also plentiful.
Links:

Calle 14 de Febrero
Panajachel, Solola 07010 Guatemala