Here are the Langford courses that I have played:
Lawsonia Links - Green Lake, WI
Harrison Hills - Attica, IN
Marquette - Heritage - Marquette, MI
Iron River - Iron River, MI
Kankakee Elks - Kankakee, IL
Spring Valley - Salem, WI
Maxwellton - Syracuse, IN
Beacon Hills (FKA: LaPorte CC) LaPorte, IN
Culver Military Academy - Culver, IN
Harrison Hills and Lawsonia you should already know about from the writeups by Ran. If you are playing Kankakee Elks CC, you should try to swing over and play Harrison Hills as well, the 7 remaining Langford & Moreau holes are worth it.
Marquette GC 9 of the 18 holes are Langford & Moreau. Greens were untouched by David Gill; however, most of the bunkering has been grassed in or redone by Gill. Course has some wild greens and a terrific short par 3 (I believe 7th hole).
Iron River CC appears to have lost some of the typical Langford fairway bunkering, but greens and greenside bunkering are untouched. Like Maxwellton in Indiana, the course does not have that completly bold Langford look. I believe this is because Theodore Moreau was not part of the construction on either course.
Kankakee Elks CC 17 of the 18 holes are Langford & Moreau. The 5th hole (a par 3) was replaced with another par 3. Why, I have no idea as the replacement hole is quite pedestrian. The original greensite was simply abandoned and is visible directly behind the 6th tee. According to the head pro, they are contemplating restoring it. Course has all of the typical bold L&M elements. The problems are overzealous tree planting (loss of many of original L&M fairway coridors)and loss of 90 percent of the sand in the fairway and greenside bunkers. Still, for the outline of the L&M bunkers and a wonderfull routing, it is worth the trip.
Spring Valley 18 or 18 holes are L&M, the hole that is just beyond the 7th green/8th tee appears to be a practice hole added by the club and does not appear to be L&M. ALL BUNKERS HAVE BEEN GRASSED OVER!!! Still I loved the rolling layout, all the old fairway bunkering is still visible, and the greens are 100% L&M. This course could be something special if the bunkering was restored.
Culver Military Academy all 9 holes are L&M according to the Academy historian, Langford laid out 36 holes. All of the L&M bunkering has been grassed over. The greens appear to be untouched and with the wild terrain, this is a very vun course.