Congratulations on your success... a very nice deal, and as you point out, any savings can go towards making your commute/travel throughout the trip a bit easier.
I'm not local to the Chicago area, but as far as i know travel at 8pm will not be an issue (i'm assuming on the Blue Line which is what takes you from O'Hare to the 'downtown' area... once downtown you may need an additional transfer). If you do decide to take a taxi i'm sure they will have one (ie- a small SUV, minivan, or one with a large trunk) that can handle your luggage and accommodate you... if you decide to Uber/Lyft there are options for a larger vehicle and i would opt for that since many of the 'standard' vehicles are of the smaller economy type and 4 people with 4 pieces of luggage would more than likely be a bit tight. Taxi/Uber pick up passengers (and their luggage) at the airport all of the time, so they should be prepared to accommodate families of 4 (or even 5) plus luggage.
To add, i highly recommend any location of Lou Malnati's for an excellent rendition of Chicago Deep Dish.
Thank you for sharing your win and using the PRICELINE links on the board to begin your bidding.
Have a great trip!
EDIT TO ADD: i don't use Uber that much, but i just checked on my mobile, they have a class of service called 'UberXL' which accommodates up to 6 passengers, so a vehicle such as this should easily accommodate 4 people with luggage (they also offer UberSUV but this is substantially more expensive than UberXL and i suspect that 'XL' should meet your needs unless all 4 piece of luggage are extremely oversized)