The Landesmuseum at the Schloß Gottorf in Schleswig, Germany (near the Danish border) should be one of the first museums on your list if your travel plans include bog bodies. The museum holdings include at least five bog bodies and and one head, though not all may be exhibited. 

The two most famous bodies are known as Windeby I and Windeby II. Windeby is an estate near Schleswig that contains a small bog. In 1952, the owners decided to cut the peat and sell it for fuel. Shortly, workers discovered the body of Windeby 1 (originally thought to be a girl, the body is now known to be male). Although the peat-cutting machinery had already severed one leg; a foot, and a hand, work was stopped immediately to study the discovery.

A short time after the discovery of Windeby I, a man's body (now known as Windeby II) was found sixteen feet away. Windeby II had been strangled first and then placed in the bog. Sharpened, forked branches had been jammed into the peat around him to make sure that he stayed put.

The three other bodies displayed in separate dioramas are men from Damendorf, Rendswühren, and Dätgen. All are named for the areas where they were discovered, and all were apparently sacrificed. 

But the most interesting "item" discovered from nearby peat bogs is probably the one from Osterby: a man's head, which was wrapped in a cape made of deerskin. Although peat workers searched for its body, none could be found, and scientists speculate that the Osterby head alone was used as a sacrifice. It has a full head of hair, arranged in an unusual style: one section of hair was twisted and woven into a figure-eight knot--without the use of a fastener.

Visit the bog people exhibits. 

In a nearby building called Nydamhalle, the remains of a Viking boat, excavated from a Danish bog, are displayed along with a number of intriguing artifacts discovered with the boat.

My only complaint about the museum is this: not too many years ago the bog bodies were displayed in a back part of Nydamhalle in a much better area. Now, they have been moved to the main museum building, in a relatively small space. Their display is fairly thoughtless now, but Windeby I is one of best bog bodies to visit, should you have the chance.