Memmingen

Go to www.bahn.com and put in Guenzburg LEGOLAND in departure station, Memmingen in the arrival station, date and time. Voila! There it is.

The only reason I can think of to go to Memmingen is to fly (RyanError) out of Allgäu Airport in Memmingerberg. Using the Bahn website, put in "to: Memmingen Allgäu Airport, Memmingerberg" (the site will prompt the entire destination before you're finished typing). The route takes a little over 2 hrs and includes a regional train (AG) to Ulm Bahnhof, followed by another regional train (RE) to Memmingen. At the Bahnhof in Memmingen you catch a 15 min bus to the airport. A full fare rail ticket, Günzburg to Memmingen, from the Bahn is 14,80€/adult (children under 15 free with parent). The bus fare is 3,00/1,50€. Günzburg is in Bavaria, as is Memmingen. The route goes through Ulm Bahnhof, which is in Baden-Württemberg, but a "border" station for the Bayern-Ticket, so if you have several adults, that might be a better option. The Bayern-Ticket probably also covers the bus to the airport. ETA: According to the Memmingen website, the Bayern-Ticket is not accepted for travel on the line to the airport.