M.R.
I'd like to throw in yet another vote for the architectural boat tour. Take the one that actually winds through the river and the city, not the one that goes out on the lake.
If you want something 'touristy' and cool with a view, go to the Hancock building and take a trip up to the observatory deck on the 96th floor. You can have drinks and appetizers up there. Another one of my favorite restaurants is the Chicago Firehouse. It is located on Michigan Avenue in the south loop, but not so far from downtown that it is a stretch.