The main floor does NOT let you see the action imo.
Dress comfortably and be able to peel as it can get quite warm sometimes, and stuffing something behind your hard seat can simulate some lumbar support. Don't forget your cough drops, and sound really travels there so shhhh. Magic happens.
The CSO is AMAZING in their flexibility to accommodate reasonable requests to move around, swap, turn in, leave for friends at will-call etc. ask them. Really wonderful caring volunteers and staff at the CSO, thank them when they do something amazing for you. Try not to miss the talks downstairs an hour before the Symphony starts by experts who will do a wonderful job of setting the history and context of the time, composers and the specific conductors and performers. We have a limited classical library and can often find very helpful youtube clips of performances around the world in preparation for the Symphony.
Transportation is easy and varied and about a 15 minute walk to the Ogilvie station plus plentiful bus and cabs. LOTS of choices to wander and eat around there, right across from the Art Institute. We often go to Millers Pub as early as we can to avoid the crowds, get a booth and ask their seasoned servers what we should have