>The adjustable screen is an attractive feature for taking photos on difficult angles.
I used TLRs for years, and like the ability to shoot at waist level. The articulating display is good for that.
>When do you use the D3000 over the D5100?
I am working on two personal projects. One is abandoned buildings, the other is waters edge. When I go out to shoot for either of these, I take the D5100. I want its higher resolution. In lower light situations, I also use the D5100.
I grab the D3000 for more casual uses. Family shots, when I am just walking about and want a lightweight DSLR. Mine has a wrist strap making it easy to carry.
I am sure the D3000 could meet all my needs, but I like the D5100.