Right now I live in Valley Ranch (Irving) on the first floor in a west- and exterior-facing unit. I believe the direction of the windows affects the temperature more than the floor, but I could be mistaken. Things I hate: hot all summer with the afternoon sun; loud af kids running and playing upstairs (officially complained twice, that helped a little); people walking on a pathway 10 feet from my patio door so I can't open the blinds/door for breeze cuz I don't want people looking at me (dog also hates them); and constantly hearing cars driving on the street 30 feet from my patio. Things I like: now that's it's fall(ish), the sun helps warm my apt. As you know, the heat is a much bigger concern here in Texas than the short kinda-winter.
I'm looking for a new apt now in Addison or far north Dallas (lived there before) with the gf, we're officially moving in together. Choices of what unit you want are extremely limited if you're trying to find a move-in date close to the end of your lease to save the most $ possible. However, if needing a tiebreaker between units/complexes, we'll look closely at things like we're discussing here. My dream apt would be east facing so the apt wouldn't be hot all summer and the sun would help me wake up naturally in the mornings. A nice view and shade from buildings/trees would be nice, but those two are conflicting. I would say top floor...BUT I don't believe kids will be a concern in the new neighborhood. A bazillion Indians and their kids live in my hood for the Coppell school district, and their kids are really loud. So, I'd say bottom floor because it makes it easier to deal with the dog, and occasional reasonable noise above, such as one or two adults walking normally, doesn't bother me.
Good luck finding reasonably priced LEED apts. They're much more likely to be built in the 21st century, meaning $$$$.
If anyone knows decent-to-nice and reasonably priced apts around Addison or far north Dallas, please share with me! Maybe the OP could describe the general area he's looking in as well.