Going back on topic....
Crunches, planks, lunges and squats. I hate them all but damn does this combo work, especially if you mix some cardio in. I did a 30 day challenge using all of these minus lunges and I saw a massive improvement.
That being said, some people will NEVER have a space between their thighs. I am one of those people, even when I was running close to 10 miles a day for cross country, my thighs still touched. What you can hope for is a muscular, healthy physique. BE HEALTHY, that should be a goal as well. Don't base your worth on your looks.
Here is the squat, plank, crunch craziness I made up. I did 30-45 minutes of cardio three times a week while I was doing this.