That would work, too. I have had training plans that have me doing everything from 400s, 800s and even mile intervals. I have also done them in a pyramid where you start off doing 200 hard, 200 easy (do 3-4 of these), then 400 hard, 400 easy (do 2-3 of these), then 800 hard, 400 easy (do 1-2 of these), 400 hard, 400 easy (2-3), finally back to 200 hard, 200 easy (3-4). The minimum distance for that workout would be just over 5 miles, plus your warm up and cool down, both of which is important when doing speed/intervals.
"God gave you your body as a gift, so you should take care of it." - My Mom