You also have to step back and look at what kind of musicians you have in your band... You can't play Led Zeppelin or Queen if you don't have a decent guitarist and singer... much like most other prog stuff... Check out "The Widow" by Mars Volta... Omar Francisco Rodriguez is a good song writer and their style is a little bit like a Led Zeppelin style... not much like anything you hear these days... Also... John Fruscianti from the Chili Peppers plays guitar on the track... Thats one song that I don't think would be really difficult... Other than that... do some research and see what bands fit with your musical influences... style... an ability to play... good luck.