I highly recommend
Ottobre which usually has several long sleeve dresses or shirt patterns for children with each magazine. These patterns are for the more experienced sewer, but if you have enough patience you could figure it out.
The magazines are available to purchase separately, but I suggest splurging on a subscription. I adore mine and jump for joy every time a new one comes in the mail.
Check out this thread for more information on how to buy these magazines:
http://www.sewmamasew.com/forum/index.php?topic=1269.0And here are some tips on sewing with the patterns:
http://www.sewmamasew.com/forum/index.php?topic=1188.0