For those who don't know, Koichi Sugiyama was already fairly well established as a composer before he got started in video game music for Enix (he was in his mid 50s at the time). In addition to film scores, he wrote a number of songs for popular bands and singers, most notably the Tigers. Quite a few of his older compositions are available on YouTube now; here's what I was able to find. I've starred the ones I particularly like, YMMV.

Legend of Sirius:
Cantata of Love
Night, Go Slowly (*Instrumental)

Ultraman Returns

Space Runaway Ideon Opening Theme

*The Village Singers - The Flaxen-Haired Maiden (Hitomi Shimatani cover)

The Tigers:
*Glorious World
Jinjin Banban
Forgotten Lullaby
*Necklace of Flowers (English cover by Leslie McKeown)
Romance in the Milky Way (English cover by Leslie McKeown)

The Peanuts:
Fugue of Love (Engrish version) (Dance remix for Angela)
*This is Goodbye
Sorrowful Valentine(?)
Sad Tango

Garo:
Your Birthday
Cafe in a College Town

The Candies - Heart Burglar

By the way, instrumental versions of The Flaxen-Haired Maiden and Necklace of Flowers were played as an encore at the 2002 Dragon Quest IV concert and appear as the last two tracks on the album, if anyone was wondering what that was about.

Niiiiiiiiiice.