The day before a big ride/race, I like to do an out-and-back route that is about 12 miles with two hills at the end (route ends at top of second hill). I pound it hard on the flats to the hills, hit the hills hard (3 climbs), and then take it easy the last 4 miles home.

I have found this works best for my legs to feel great the next morning, but everyone is different.