Despite my many attempts to resist, the practicality of a bicycle has finally convinced me. My father is dropping off his old late 70's Schwinn Le Tour road bike. He used to do distance rides with it in the 90's; I would be using it as a school/work commuter and general city bike...it's a 27" with factory race bars and the hardest berkeleying seat on the planet. My dad calls it the "vajajay buster"...yeah. Any suggestions for modifications or first steps to take? It seems kind of heavy for having such a dainty build. I'd like to customize it a bit and make it my own. Looks almost exactly like this:

I rode a LeTour in college. Decent bike. Ditto on the seat comment.
Get pictures of the serial numbers and paint something distinctive someplace a thief wouldn't readily find it (like the bottom of the seat post) to aid with identification if it gets stolen.
Beyond that, don't sweat making it your own. Commuter duty may break it very quickly, and if it holds up, you'll make little changes to make it more comfortable, utilitarian, whatever.
I miss my bike legs. I ought to start riding to work.
modern saddle
700c rims
8- or 9-speed rear cassette with matching derailleur
brakes that will reach the 700c rims (ask Gamby)
PHeller
SuperDork
9/14/12 2:21 p.m.
Wide 700C rims plus fenders. Fit largest tire possible.
Riser bars, old mtb brake levers, friction shifters.
I gave a LeTour of that vintage to a friend of mine, so far he's ridden it back and fourth to school/work for 3 years and only put new tires on it.
Don't bother adding lightness. It's the frame itself that makes this one so heavy. Best upgrade would be a nice set of aluminum modern 700c wheels, so long as the brakes will reach. I'd upgrade the brake pads first for better stopping power.
I still have a Le Tour II I bought in the late 70s, although I only get it out a couple times a year these days. Mine is orange but otherwise looks like the one in the picture. I put flat bars and a better seat on it, and it works well enough for me for just riding around the neighborhood.
You'll want to try out a few different seats to see what fits you and your sit bones best. WTB makes excellent seats. I'm rocking the WTB devo and it's the best I've found in my 22 years of riding bicycles.