Just a couple of thoughts/questions:
Does it have to be literally on Mich., or just generally in the area?
Haven't been to Kiki's in a while, but they've been around for a long time and have, as far as I know, maintained a rep. for consistency. When I was last there the general feel and pricing seemed to push "bistro" to the upper edge, but it was very nice.
I've had a couple of very nice meals at Margot, but I've read reports of other people being disappointed. Another possible issue is your definition of "romantic." Margot, and many other bistros, tend to be rather bustling, closely spaced places as opposed to quiet, dim, and private feeling. If you find the former "romantic" then, great. But if you're expecting the latter, you might be disappointed.
I've had some very nice meals at Bistro 110, but it was always on the crowded, noisy side. Maybe celebratory for a group, but I wouldn't call it romantic.
Used to be a fan of Zinc on Southport and a few good meals at the downtown one, but the orig. team parted company long ago. Don't know how the place has held up over time. One almost never hears of it in general eating conversation, whatever that may mean. Possibly nothing.
Finally, if it's not too far afield, consider
Cyrano's Bistro. Don't have the address at hand, but it's pretty much Wells and Grand. (within a block or 2 of those coordinates)
"Strange how potent cheap music is."