If you don't mind a slight case of wind chill in the winter, then a riverfront property is a great bet.
As with everywhere else in the world, finding a clean, well-run and affordable apartment is going to be the most important aspect of your decision.
You may be used to the Red Line if you're coming from Chicago, but don't count on reliable, or even robust, public transit in St. Charles. If you live downtown, walking, running or biking are fine options to get around, but a car is essential for trips further away than your local coffee shop.
The river is a focal point both for community activities and festivals. The annual Riverfest kicks off the summer with a fox hunt (not the furry kind - the clue kind), Dragon Boat races and a carnival. When the river isn't occupied by giant wooden dragons or sailboats, locals like to stake out a place on the banks for some fishing.
If you're in need of some permanent rest and relaxation or if you're ready to leave the city and its denizens behind, then check out St. Charles. It's a pretty foxy place to be.