I enjoy heavy squats, they're hard, no one likes to do them, but they make your legs strong and tight. I superset them with leg curls, good mornings, straight leg dead lifts and calf raises. Then I wrap up the session with some ab work. Currently, I'm doing some new abs stuff called "Core Max" which includes planks, levitations and gravitational ab work. Tough. Plus the traditional crunches, reverse, and the rest. The ab routine takes about 20 mns. and the leg workout about 45mns. This morning I had no energy, and tonight, I am burnt. So I only did the abs, no legs....I always feel disappointed when I miss a day, but tomorrow will soon be here and I'll get back into my squats.
I work out 6x/a week. 4x with heavy weights and 2 days of treadmill, abs every day.