Preferences for gearing are a personal thing. I, for one, do a fair bit of long distance riding (just gearing up for PBP again), and I don't have a need for very small gears (a 39-27 will be my smallest for PBP). In the vintage department a cheap 14-28 cassette is perfect with a standard front for me. I find changing the cassette has less of an impact on the appearance of the bike. I'd hate to lose the black DA.
But it sounds like you may have your mind set on smaller rings? As above, I'd get a 110bcd Sugino from the parts bin and keep the DA in storage as the original equipment for the bike or you'll regret it one day