I agree with Kelly on the order of choosing a date, but for different reasons.
The latest date would be my first choice - purely from a sanity point of view. If you have a later date, its not so disappointing when you miss the earlier EDD.
I know my cycles are 28/29 days, and I know when I am due based on everything, but luckily I've only been out by 1-2 days throughout my pregnancies - so I'm not having to deal with these big dates that you are.
I personally would tell them fine on the later date, but I want closer monitoring towards the end to make sure that you aren't going too late.
What a PITA though!!