The only way to really relax with a three month old baby is to ask Grandma to babysit while you and hubby go away - anywhere.
I don t think Detroit should be a good idea lol try Minneapolis!!! It s beautiful!!!!! And its only a 1hr flight from Chicago. There s plenty of nice places to just relax and they have the largest mall in the world, The Mall of America which is 5 min away from the Minneapolis/ St Paul Airport, the hotels r very cheap, we stayed at the Holiday Inn Express in Bloomington which is 10 min away from the airport and 15 min away walking distance from the mall and we paid only 180 for the whole weekend (thurs, fri, sat nights) in a room with 2 queen size beds. besides the light rail will take you anywhere from the mall all the way to Downtown Minneapolis, theres also Minnehaha Park and the light rail stops there, its abeautiful park next to the Mississippi river.... and the weather should be the same as in Chicago right now...if not come to San Francisco!!!! lol Greetings from Sacramento CA
I would consider a road tip to Madison, WI - its a young and hopping place.
west michigan, grand rapids, grand haven, kalamazoo has a lot of cools stuff too