Complex sentence: The band had been invited to perform at the August 1969 Woodstock festival but declined, instead electing to embark on a train tour of the United States, which ultimately ended in disaster due to drug and alcohol use.
Split into simpler sentences: The band had been invited to perform at the August 1969 Woodstock festival but declined. Instead, the band elected to embark on a train tour of the United States that ultimately ended in disaster due to drug and alcohol use.