Did you read, including links, the responses you've already received? Have you discussed with your client their goals, short- and long-term? Have you discussed with their lawyer?
An MMLLC defaults to a partnership in non-community-property states. If NOT an LLC, husband and wife can have a QJV and file on their joint Form 1040, but that doesn't give them the protection of a separate entity that you say they want/need. They can still get good insurance for any option.
Are they expecting their children to inherit the LLC? Ask the lawyer how that works in IL. (Do they get a step-up in basis or not?) Or, do they want to gift it over time, maybe a % each year?
Ask your clients what their goals are. Then discuss with the lawyer how to achieve those goals.