celinemae...I'm a veteran mom. I recommend that you rent a car at Ohare to travel to Great Lakes. That's what I did and am so glad that I did. Public transport can be unreliable, inconvenient and expensive. The roads in that area are not bad and as long as you don't plan on driving to Chicago you should be fine as far as finding everything. I took a GPS (you can rent one as well with the car). Make sure you have addresses for everything...hotel, RTC, restaurants, the airport, etc
I plan on taking the Metra into Great Lakes. There are a few stations in the area depending on where you're staying. And some hotels pick up from the stations, otherwise there are taxis. The most it will cost is $8.50. I would suggest if you go that route to familiarize yourself with the trains before showing up so you don't get lost.
Call SARGE - He is our "go to" guy for transportation! 1-847-212-0246 He charges by the car not the person...so if a few of you can get together it helps. Either way his prices and his CARING for us is the best! Not to mention that he takes care of our Sailors in Great Lakes A School!
If you take the Metra to GL you will still need transport to your Hotel...so I would still recommend him.
I'll post a Metra Link.
Congrats!!!! My daughter (Aircrew) recently graduated. We used (Juan's Taxi Service 847-980-4537 ) he was very prompt, dependable and professional. He has very reasonable rates and charges by the carload, not per person. If he has more than one pick-up at the same time he divides the cost. We used him the entire weekend and was very pleased. He has tons of information as he has been doing this for years and can answer any of your questions. Good luck.