I would say you are on the right track by joining the forum! Start searching around here for a general idea of what you'd like, then that will help your TA find you the perfect place.
So, places to start:
Obviously you said you need children.
Do you want all-inclusive?
Do you want close to town?
Do you want to be married in a church, gazebo, beach, or garden?
How far from the airport do you want to go?
Do you want to be close to activities, like cenotes or Xcaret?
Do you want a large resort or a small quaint resort?
Do you want many dinner choices, or just a few?
Do you want your reception indoors or outdoors?
And most important... what's your budget... and the budget of your guests!!!!