You can get a lot done here in 10 hours. A short walk east from Union station is the Sears Tower. There's an observation deck. Assuming, it's a clear day, go for it.
There's tons of stuff to see and do here - it all depends on your particular interests. Take a look at the Chicago introduction page on this web site. Also check out www.metromix.com for other ideas, including dining suggestions.
You could go shopping on State St. and probably even quickly fit in Millennium Park. The Sears Tower is also (as Dave mentioned) an excellent idea, although I'd watch the lines - if there's heavy or mild lines, I would reconsider.
The one issue is that Amtrak does tend to run a little (or sometimes a lot) late. While you can do a good deal in 10 hours, you may have to reevaluate your potential plans on the day.
Your 10 y/o might enjoy the American Girl Doll Store if she's into that. Across the street from there is a Gharidelli (sp) shop that has the best ice cream. There may be a free trolley outside the train station that can take you there. I've done it before, but I am not sure if it runs in the winter. Someone else may know.
LadyPhoenix, let me preface by saying that I have not taken your specific route with Amtrak, but do travel on it often. My advice to you is to not plan on having a 10 hour lay-over but considerably less time - maybe only a couple of to a few hours, if that.
It is even possible that you may not have any lay-over time to speak of at all if the train is considerably delayed.
If I were you, I'd pick a few choice options and determine how much time you would be spending there for them to be viable - and comparing it to the cost of those options. Then when you finally get into Union Station and know for sure your lay-over time, pick which you can do then.
You'll also need to remember into take into account the additional time for all of you to check your baggage, return to Union Station from wherever you are, reclaim your baggage (and, by the way, have you checked what you can do with it when you are exploring?) and have boarding time for the train before its departure.
For example, if you went to the Shedd Aquarium or Field Museum, I'd plan on spending 4 hours at least at either museum (if not only for the cost but to actually see something there) and another hour for traveling there and back - by cab. With a bus or the free trolley, you'd have to factor in additional time for waiting for it - and, especially for the free trolley, more additional time in case you couldn't board the first one you see due to its filled capacity.
Or if you went on the Chicago Architecture Foundation River Cruise (if tickets are available when you are there), you'd need at least 20-30 minutes to get to the boat boarding area - by cab, .25 hour for boarding, 1.5 hours for the cruise, .5 hour for the return trip to Union Station (and picking up your luggage, etc.) and .25 hours for train boarding (total 3 hours).
Or if you went to the Sears Tower, even though you only need to walk east over the bridge from Union Station to it at Adams/Wacker, you'd have to wait (and sometimes a considerable amount of time - see recent reviews) in line to even get to the observation deck. So I'd plan at least a couple of hours for even this.
I hope you don't take this as a pessimistic view, only a realistic one. It would be better not to disappoint your 10-yr. old by saying that you were going to do something special, only to have to say "Sorry, we just don't have the time for it" when you get into Chicago Union Station.
Oops! Sorry I meant to mention that your post doesn't say when you are traveling. If you are traveling during the winter or early spring, you would have different choices than in summer, for example.
I indicated the Chicago Architecture Foundation River Cruise, if you were traveling when it is running.
We'd travel in August. Thank you all for your responses. And no, I have not found out yet if there will be a place to store our luggage...but I've been told that for those with First Class accommodations (which is what we'll have for the 13 hour trip to and fro Mississippi - Chicago), there is a place to secure luggage, but I am still researching this...
I'll suggest Navy Pier. Indoor and outdoor activities, places to eat and drink, alot of kids activities and music. Free admission. One of my fav places. Did I mention the view?
With reference to your bags -- Amtrak DOES have a lounge & luggage storage at Union Station for its first class passengers.
Once you de-train in Chicago and have gathered your luggage, head straight to the Metropolitan Lounge. This lounge is reserved specifically for first class passengers and is where they will hold your luggage for free. The Metropolitan Lounge has complimentary drinks, comfortable chairs and couches, a TV, and clean restrooms. It can be a little difficult to find, just ask for directions if you have trouble.
i am traveling to ma. next month and have a 6hour layover at union siItation in chicago.. what is there to do there for 6 hours!!!!!!!!!!!!!!!!!!!!!i dont want to leave the station so is there a lounge or cafe inside there ?please help me ,first time traveling on amtrak..email@example.com