In case anyone was wondering:
StarfallStar Fall (1980) by David Bischoff, the first in the "Star Fall" series. (ISBN: 0-425-04524-2)
It has taken the combined genius of Human and Morapn civilization to create Star Fall, the vast interstellar liner with luxurious accommodations for every type of intelligent life in the known galaxy, now booking for her maiden voyage. This historic cruise will take her to the legend-shrouded center of the universe itself, old Earth, where her arrival will usher in a new era of peace and understanding.
Or so the brochure said. But someone, or something, hadn’t read the brochure. For hidden on the Star Fall is a box of anti-matter.
Just a small box ... one that is just large enough to implode Earth.
I finally found the right combination of keywords to find it in Google. :)
Per ISFDB, it has a sequel called Star Spring (1982).