A few issues I see. First, @Mike S. is correct, putting a single trust into the LLC would make it a single-member LLC would could forfeit some liability protections. Your living trust will not give you any asset protection.
Second, one of the estate planning benefits of owning property in an LLC is that you can put the LLC interest into the trust without transferring title to the property (in most states).
Third, if someone wants thier children to take over the business, not just inherit it, they must also include some business succession planning within your LLC to make sure that happens. What happens if one kid wants to pursue the business and the other doesn't? How do you avoid a liquidation?
Here's the real takeaway - if you have rental property and an LLC, it's probably worth having an estate planning attorney (with business and real estate investing experience) put together your trust. They'll cover these issues.