The Subway is in Zion.
http://www.canyoneeringusa.com/utah/zion/subway.htm
It is well worth the trip. It can be hard to get a permit but they do keep a few "walk in" permits in reserve.
Tom's page says there is a 30' rappel. That isn't exactly true. There is a spot where some people use a rope to downclimb. I usually take a long piece of webbing "just in case" but more often than not there is a line in place.
If you can get a Subway permit I feel it is well worth the trip. It is a little more wet than Orderville but keeping your gear dry with a dry bag wouldn't be very gear intensive. Just a bag and possibly a line to lower your bag off of some of the downclimbs.
One HUGE consideration... The canyons change quickly. I have done a canyon that was supposed to be a 1 and ended up needing gear for a 3. I have also taken gear for a 4 and ended up walking thru like it was a 1 or 2.
The people at the backcountry desk are usually really up on things. In the old days there was a book where people left trail notes and updates but I think the park does something more formal now.