I have only been monitoring seriously for a year but have had 2 successful dee fledgings-both from Gilbertson PVC boxes. One box faced south and was placed under a dogwood tree next to a forest edge in the back yard. The other was next to the driveway, facing SW with nearby evergreens and backed by a 6' solid fence. That box fledged 5 (or 6 because the nestlings were crammed in so tight and my monitoring was really fast cause mamma dee was NOT happy).

4 out of 6 EABL nestings were in wood boxes and 2 in Gilbertson PVC. The blues did not bother the dees in any way but I either placed the box out of sight of the blue house or far enough away (at least 80')with the entrance hole facing away from the blue's house.

Dees are wonderful little birds, stay year round and are always at the feeders. To open a dee box and see those tiny nestlings all dressed up and hunkered down is sheer joy.

Amen to those adorable chickadees.......Jane

You will find helpful information at the web site linked below. Click on Nestboxes, then Placement. This provides a listing of the preferences of all the cavity nesters. You can use this info as it applies to the habitat you have available for your nestboxes. For example, chickadees might prefer more of a tree canopy, and bluebirds might prefer a more open location. I say "might" because they also like to keep us guessing LOL. There may also be other things they consider when choosing a home which we humans know nothing about, such as a preference for the same type of habitat or nestbox in which they were raised.
IN ADDITION! You might want to carefully add a hole reducer for the chickadees to prevent harassment by larger birds (even the bluebirds), or even protect them from house sparrows. Nestbox specifications on that same web site will give you the recommended size, and there is even an entire page on hole restrictors under "Problems and Solutions" which mentions WHEN and HOW a hole restrictor should be added to avoid scaring the chickadees off.
There are also some hints on the link for "Nestbox Pairing."
The direction your nestbox entrance faces might not be as important as the location, as the birds will often perch on top or nearby to monitor their territory or enter to feed their young. Lots of considerations such as prevailing winds, amount of cover, visibility, etc.
You will also find IMPORTANT information to prevent climbing predators - refer to the page on Predator Baffles.
Bet has provided us this wonderful resource, collecting input from everywhere and everyone. Thanks Bet!
BlueBars

Here is a link that might be useful: http://www.sialis.org/index.html

I agree that chickadees are wonderful little birds. I was fortunate to have a brood in a bluebird box in April 2007. I went through my notes and photos and you can see some of them at the link here.

Linda...

Here is a link that might be useful: Cute little chickadees.

Funny someone should mention about the birds keeping us guessing. Three years ago I moved to a house on a wooded lot and gave my 3 nest boxes to my dad (who has 6 boxes on 15 acres now and has fledged alot of TRES and blues) because I had read Blues liked open spaces.

Well in those three years I have continually seen Blues in my yard, and I've seen more than usual this year. It's a good thing that the 2 Gibertson PVC boxes I ordered a week ago arrived in the mail today, they're going up this afternoon and we'll see what happens.