Sondheim shows are almost always best represented by the original casts, coached by the composer and in several cases written for the specific vocal strengths of the original stars.
WEST SIDE STORY, GYPSY and DO I HEAR A WALTZ? are all well represented by the OCR's - all available on CD from Sony.
FORUM has two decent cast albums. The original has the unbeatable original cast. The Nathan Lane revival is very good as well but suffers slightly from a reduced orchestra and a few trims here and there.
ANYONE CAN WHISTLE - While the concert cast provides some insight into some brief sections left off the OCR is under rehearsed. The OCR is so slick that those who hear it wonder why the show failed (until they read the synopsis.)
COMPANY - Sony’s remamster of the OBC is about as good as you'll ever get. The London version, which had Larry Kert overdub Dean Jones vocals, is not a satisfactory mix. Weak voices sabotage the 1995 Broadway and 1996 London revivals.
FOLLIES - Despite the maddening cuts, EMI's OBC is essential for what it does preserve. Piece together the missing segments from the Papermill Playhouse cast or the Lincoln Center Concert cast. Avoid at all costs the 1987 London revival.
A LITTLE NIGHT MUSIC - OBC is the hands down winner and virtually note complete.
PACIFIC OVERTURES - The OBC is in need of a sonic upgrade - it was one of the first CD issues and we've come a long way in remastering since 1986. The recent revival cast is interesting but the original performances are more polished. If you really like the show TER's 2 CD set of the entire show (with all dialogue) is a must.
SWEENEY TODD - Nothing touches the original. Both the Concert cast and Broadway revival feature Patti LuPone and offer interesting alternates.
MERRILY WE ROLL ALONG - The problem here is that the show was rewritten and altered after the Broadway cast album was done. It presents a brassy Broadway sound that serves that material well. Of the two later recordings the 2-disc Jay/TER release includes the complete score as well as quite a bit of dialogue. (The RCA OBC is out of print. It is slated for reissue but it keeps getting delayed. It will be worth waiting for as it is said to include additional material left off the original issue.)
SUNDAY IN THE PARK WITH GEORGE - The OBC was a masterpiece of cast album production and an essential disc. The recent London cast has more dialogue and records some sections in the way they are performed on stage, while the RCA cast album made alterations for the home listener. (Ie. "The One on the Left" is included in "The Day off" instead of after "Everybody Loves Louis.")
INTO THE WOODS - Nothing beats the OCR. The London cast is a rough listen. The 2002 revival has its moments but is not nearly as enjoyable as the original.
ASSASSINS - the original off-Broadway cast give the best recorded performance but the revival cast includes "Something Just Broke" write for the London production and now an essential part of any ASSASSINS production.
PASSION - Angel's OBC weaves together dialogue and music into a beautiful 60 minute distillation of the show. The London cast is about 15 min longer and has a stronger Giorgio in Michael Ball but the female leads are miles behind their American counterparts.
BOUNCE - Still a work in progress but the Washington cast album reveals a lot of strong material in the score.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com