re: What sounds like the better workout? Swim 1 mi., run 5 mi., or bike 25 mi.?

The running is harder than the biking. Sure it's not tough to run an 11 minute mile pace, but run constantly for five miles, nearly an hour. Those that don't run and aren't conditioned will be wiped out after running 5 miles. Especially in the summer time.
Swimming is way harder. You can't really rest, unless you hang on the side of the pool each lap.
Biking you can coast some.