Lunges and Squats give you great shapely legs
Done with extra weights (using a barbell on your upper back and increasing the weights as you get stronger) will do wonders.
Then,
As cosmicgirli said, Use something like Pilates to then release your muscles so they're not so tight so that they can be nice and 'lengthened.' (you can't actually make a muscle longer)
Of course, you have to make sure that you've got a good healthy diet.
spinning gives great legs
so does running
but it depends on your genetics of course. some people feel that running or spinning bulks up their legs.
I agree with this. Getting muscles is nothing to be scared of girls, you probably wont get them anyway!
Another thing I'd like to mention is riding. It's not ideal as it needs, well, a lot of equipment and some interest - but riding classes once/twice a week does wonders for stomach, butt and leg muscles - and you barely notice it when you're riding because you're so concentrated on what you're doing.