For me, Space Quest III probably had the most memorable of the Space Quest soundtracks. This was the first of the Space Quests where they were starting to get serious about the soundtrack. In fact, if Wikipedia is to be believed, Bob Siebenberg, who composed music for Space Quest III, was the first major artist to compose original music for a video game. There you go folks - and the year? 1989.
The Introduction track is energetic and fast-paced; it really gets you in the mood for another adventure as the galaxy's greatest janitor, Roger Wilco.