I use spinnervals, they make the time go faster and help keep you honest. I ordered up a couple of new ones for xmas the Hardcore 100, should make a good Sat. workout. Its nice to have a few so that you can shuffle up the pain a little. Ask Santa for a Heart Rate Monitor the two work well together.
It seems like a DVD which is like a ride in the park or some nice mountain ride would be good, but unless you actually work the training time is of limited value I think. I do think the spinnerval series gives a good workout given the time you spend.
Best of Luck
My goal is to use up some of the old tires I keep around while I loose some of my spare tire!