OK, lots of good advice, thanks. Here's where things stand now:
I've decided to refurbish the broken Raleigh but not to use it for commuting. I found a TIG welder who repaired the break and I'll give it a thorough rehab, new paint, even new decals from Raleigh to replace the originals. I'll figure out later if I want to keep it as a spare, sell it, or give it away.
I plunked down $80 for entry level Shimano shoes and pedals to try clipless riding on the 12-speed steel 19802 Miyata. I'll commute on that while shopping for something newer.
I'm making the rounds of local bike shops, taking notes and thinking about what to road-test. The REI store was quickly scratched off my list. They had lots of bikes but didn't seem to know much about them. Performance Bicycle impressed me. They spent a lot of time teaching me about clipless system and talking my bike options. Two of the salesmen race their bikes and seemed to enjoy the challenge of finding the perfect bike.
First critical variable: bikes with attachment points for a rack. Few of the road bikes had them so they suggested a cyclocross. I definitely want something with drop bars so I can stretch out on the bike and use different hand positions. Is there a down-side to cyclocross bikes? Is the center-pull brake inferior to side-pulls? I like the idea of being able to go with a slightly wider tire.
My commute is 20 miles a day over asphalt (some of it bumpy from tree roots), some hills, and about a mile of very busy streets at one end.
Thanks again for all your good comments!