Here are my questions:
1) Is a roundtrip cruise from Grand Haven to Chicago feasible in our 25 footer given a time window of 10-14 days and the above constraints?
2) Are there any decent ports for an overnight between New Buffalo and Chicago?
3) Any tips for staying a couple of days in the Chicago area? Marinas? Moorings? Etc.?
First let me tell you about me, we were moored in Monroe Harbor; Chicago for over 25 years, we now sail out of Holland (just South of you), we routinly sail to Chicago at least two or three times a season but we do the open water 85 NM route.
You are fimiliar with the ports as far South as South Haven correct?
Well next is St. Joes which is about 20NM's
Than New Buffalo,
Than Michigan City is about 12 Miles from New Buffalo.
After Michigan City you have a couple of more in East Chicago and Hammond, but at that point you are really adding the miles under your keel.
Michigan City to Chicago is only just over 30 miles, to continue to follow the shore would add many miles to that.
If you want to be right down town in the heart of the city; DuSable Harbor and Burnham Harbor have limited slips available for transients. Call ahead as soon as the season opens and you know when you will be going.
Mooring balls are much easier to get in Monroe Harbor (also right downtown), but no shore power or water and you will have to get used to riding the tender back and forth.
I cruised our 25 footer for many years, but I did not have small children on board. Can it be done in 14 days? Deffinitely yes. 14 days is a long time for a trip like this. The big question will be can the children be comfortable on the trip and how much will they slow you. And remeber though, just because you plan on hugging the shoreline does not mean you may not get some nasty seas. In fact it might mean the opposite.
Have fun, and if you need any more help let me know.
BTW, we would love to have you stop in Holland on your way. That could be your first 20nm leg. Look us up, we are at Eldean's Z-46.