My legs are often nearly straight (steps 1 and 2 of natural turn as an example) but my thigh bone is far from over my shin bone, and i'm using a lot of muscles.
My view is that dancers have to put special effort into developing calf muscles groups and foot and ankle muscles, because everyday movements don't really use these muscles a lot. apart from climbing stairs. That's why people use lifts!
On the quickstep thing - if you like big band swing you love quickstep. Someone earlier mentioned Shout and Swing and Sing-Sing-sing.. If these don't get you going...
Anymouse pointed out that it's important to stay calm. I can relate to this. If they play any of these big band tunes, i'm taken over by the music and anything can happen!! Including admonishment (to put it politely) from my partner.(quicksep is one of our better dances)