Carla C's Easy Fit Pants pattern *rocks*!! www.youcanmakethis.com
This pattern can be used for boys or girls. After making them a few times I could whip up a pair in half an hour. They look fantastic and have an option for a contrasting band at the bottom. Carla C also has a Raglan Shirts pattern that is terrific for boys (and girls too). Great way to start working with knits.
for girls - the Sew Baby's One Piece Sundress pattern is super cute, comfy and very, very easy to sew. As is the Quick and Comfy Dresses pattern (I have even used this, modified, to make nightgowns!) Both come together quickly and look fantastic.
Kwik Sew has some good patterns.
Also, McCalls and Simplicity have a few girls dress patterns that simply pull over the head (no buttons, zippers...etc.) and are so easy and beautiful when finished. (the patterns I'm thinking of are in the 'easy' section)