I think a person can get a fair idea on general type from a good written description, but for me good photos or illustrations really help me fix it in my head. That being said, nothing can compare to seeing good examples in the flesh. Still today about the time I get to thinking I may be getting somewhere with one of my Brahma projects, all I need to do is go to a good show and reset my goals. One thing that written descriptions and pictures sometimes fail to convey, at least for me, is size. I had a pretty good idea and appreciation for a nice wide skull or back. But when you see those big ol Brahma cocks with a back so big and broad you could play chess on it, it is rather sobering. Similar could be said for the Cornish as well, although I think you just about need to have a Cornish in hand to really appreciate their true massiveness.
One of the perks of being from these parts of Ohio is we have several good poultry shows within reasonable driving distance. The Ohio National show regularly hosting many breed club's national meets, drawing the best birds from a pretty broad area. May be well worth a persons effort, if they have never been to their national club show, to take a few days and travel, if within a reasonable distance, to see these birds firsthand.