I prefer to do interval type training (bursts of high intensity alternating with rest) because it closely matches "cadence" of my hockey games - you skate hard for about a minute, then rest for 1-2.5 minutes. While indoor options can suffice, it's more fun to get outdoors and certainly much more difficult. You also get a lot more out of 25m IMO.
I've been to Edgewood a couple of times and really like it. The incline is not overly steep to run up and it doesn't kill your knees on the way down. There are short loops so you can do 1 mile to 4+. My first time I intended to do a modified version of Trailstompers Big and Small Loop (cool site btw) but took a wrong turn and my increased my intended 3m trail run to about a 5m one. This weekend, I did the Sylvan Loop, a 2.5m route which can be done without a huge time investment while still getting a good interval workout.
Quick note on Sylvan Loop - head over to the trail head near the wire link fence. For a more difficult start, head right on the Baywood Glen Trail for a series of 6-7 switchbacks and steeper incline.
