Let me toss in one more vote for the "heavy" touring bike. Note the quotation marks.
I tend to use one of my touring bikes for commuting, group rides, long weekend rides, etc., just because it's always set up and ready. I get some guff, along the lines of "You'd ride so much faster on a light bike." That's not my experience, though; when I do pull out the lighter bike, even though it's at least eight (
pounds lighter, the bike disappears within a quarter mile of getting on it. I suspect if I took off the next 40 pounds I might speed up more...
What I do notice is the load. Light commute load, hardly there. Heavy load (add lunch, shoes, coffee, electronics, etc.) and the bike starts to feel like a slug. Similar to Pete's experience, I usually find the threshold between light and heavy loads around 10-15 pounds. I usually do a couple apple runs every fall; the touring bike is a joy to ride out to the orchard, and I have to enjoy the apple cider and stop to munch an apple coming back. The bike disappears, but the load endures as long as it's on the bike.
My recommendation, as usual, is buy what you like. We're all susceptible to analysis paralysis, and subconscious influence. You read the web pages marketing the latest and greatest, or the glossy magazines with
marketing reviews of the latest fad, and it's obviously the wonderfulest thing on the planet.
After all your reading, go find some bikes and test ride them. If possible, load them up and ride them 3-5 miles. I did something like that some years ago. Called around, and the nearest place that had the model I wanted and one I wanted to try, was 200 miles away. I went down and test rode everything I could find in one afternoon, and brought a totally different model home, and rode that model across the country two years later. So try as many as you can yourself, and buy the one you want to ride.