I was very fortunate in that I did get to see the electrified MILW. But I always wanted to get into 16 mile canyon east of Lombard and never did. I would have loved to have ridden the Olympian Hiawatha in that era when they used bi-polars on the Coast division, steam on the Idaho division, the passenger Joes on the Rocky Mountain division, and diesels didn't venture west of Harlowton MT. Check out my Railroadforums photo gallery at:
photos and go to pages 6, 7, and 8 for some MILW pictures.
Another one I wish I had been more aggressive in pursuing was the Rock Island. I did a fair job on the northern part of the system but never got down to the southern part of the Rock.