Just to clarify some of the responses; as the original poster said that it is a 747 it will have the latest version of the Club World seats and AVOD - not that this changes the layout or fact that from the middle seats you may have to climb over other passengers. Also, if you have the ability to OLCI, so long as you don't print your boarding pass you can go back into OLCI and change your seats.

To the original poster - you didn't mention the age of your children, so we don't know how easily they'll be able to step over someone who is sleeping? I have been in a centre aisle seat with someone elses children in the middle seats in the row ahead, if your children are constantly getting in and out of the seats then expect the other passenger to become iritated by this so something you may need to be aware of - as you occupy one of the routes out I suspect you'll find that it is you that will get this traffic?

In the future, perhaps do what we did, put one of the children on the 2-4-1 booking and the other on the MFU'd - yes you have to pay an adult WT+ ticket rather than the two children but you'll all be able to OLCI and won't be faced with this issue.

I would imagine that unless loads are light the seats at the back of the cabin where the bassinets are will have already gone, these have inside seats with no one to climb over.