If you want to take your wife for a romantic dinner you may go to John Hancock Center, The Signature Room at the 95th.
The view there is fantastic. The food, not so great. A lot of folks go there for a drink, then go elsewhere to eat.
If you want to go for a romantic dinner with a great view, there are two places I recommend.
Everest is in the south end of the Loop, about 1.5 miles south of your hotel. It's on the 40th Floor of the Midwest Stock Exchange Building, and has a great view looking out on the entire city. The food is contemporary French/Alsatian from Chef Jean Joho, and it is fantastic. It also has a huge wine list, including the best selection of Alsatian wines in the country. It's formal (jackets required) and fairly expensive (figure $150-200/pp with moderate alcohol and tax/tip) but worth it.
North Pond is in the middle of Lincoln Park (the park itself, not the adjacent neighborhood of the same name), two miles north of your hotel. It faces its namesake pond, with the city skyline looming over the opposite shore; the renovated building formerly served as a warming shelter for ice skaters on the pond. The food is contemporary American from Chef Bruce Sherman, and it is excellent. It's fairly casual (jackets not required) and mid-priced ($100/pp).
If you want to stay within a short walk of the hotel,
Spiaggia,
NoMI (in the Park Hyatt), and
Avenues (in the Peninsula) are three of the best restaurants in Chicago; all are expensive, jackets-required places. For outstanding food that's more affordable (and a fairly casual atmosphere), I love
Cafe des Architectes, on the ground floor of the curving glass facade of the Sofitel. The contemporary American food from Chef Martial Noguier is outstanding. And it's surprisingly reasonable; they have a 3-course prix fixe menu for $42 every night, and on Sundays through Tuesdays they offer a 3-course "neighborhood friends menu" for $29.