That race in costume is epic! I was invited to do a similar one here, but alas it's the same weekend as the main convention I go to each year. Maybe next time.

On leg days I usually do a set of DB squats paired with lunges (usually walking lunges). I apparently have awesome form for lunges, but with DB squats I do them with a fitness ball against the wall for stability and support.

For abs, besides sit-ups I tend to do a lot of russian twists and also knees to chest on a bench (like this http://www.coopersguns.com/videos/exercise-encyclopedia/abdominals/knees-to-chest-on-bench/) graduating to holding heavier DBs between my feet.