One more vote for "ride what you got." See if you can mount racks on it, if you don't already have them on for commuting. Go out for an overnight ride or two, or a week, and find out if you really enjoy it. (You probably will!)

Low gears are nice, and you can probably change out the crankset for a reasonable price, maybe a mountain double. Beyond that, you're heading for "it costs more to change the components than to buy a cheap tourer and I'm still stuck with this old frame" territory. New front derailer, new brakes, new brifters (have you priced STI shifters lately?!), new bars, and shop labor -- see if anybody near you carries Fuji Touring bikes instead.