Squats and lunges work best for toning ur thighs. They dont only tone ur behind but also ur legs as well. Try push off lunges, plyometric lunges(jump lunges), jump squats, side leg raises, the pendulum(its an aerobic move where u move from side to side), jumping jacks and shuffles(or scissors) and high knee runs. Different types of kicks can help tone ur legs-i teach something called bodycombat where u do side kicks, roundhouse kicks, front kicks, jump kicks-theres loads-but they all tone ur legs and thighs-i dont know if u have any classes near u.
The only problem with cycling is that it can bulk ur legs up if u do it too much.
i would say invest in an elliptical! do it everyday for atleast 20 mins.. n watch what you eat a little... it makes a huge difference to your thighs... tried n tested!