For me it would depend on a few things.

1. How long are you planning on going?
2. Do you have the spare $$ for ALL of you to go?
3. Do you have someone to watch the kids while your at the wedding or is is kid friendly?
4. How close are you to this person, would they do the same for you?

Personally for me i would either go child free for a shorter time (the cheaper option) OR all of us go.

If i were going i would want to make the most of enjoying the wedding with a really great friend, if you had just DD1 would you need to leave early to put her to bed and the like?
If ALL of you were there would you need to leave early, i couldn't think of anything worse than flying all that way for a wedding i can't stay at all night IYKWIM.

If you think the flights would be fine and you have the $$ and you would get to ENJOY being at the wedding then i would go as a family and make a little holiday of it... would DP be willing to maybe look after the kis while you party on at the wedding?