One of our favorite venues in Lemont is Cog Hill http://www.coghillgolf.com/weddings. You don't have to be a golfer to like this place. You can have a ceremony outdoors then reception inside their rustic dining room. Our experience working with their staff has always been great.
On our blog we have a recent wedding at Cog Hill, and the beautiful church was also in Lemont at St. Alphonsus.