Thanks Julie. Those are some of the reasons I'm starting to work with this stuff "on the side." I need to get things all worked out before I try to offer anything like this.
On the pure blue like I posted the other day, I can lower the opacity of the clouds layer to show some of the curvature of the backdrop before the filter. For that one, the background wasn't replaced. I could also go with a little less even lighting to give some depth.
For the one above, I'm thinking about a sled to position the dog on. It will take a bit more work blending the shadows and light to the background to make it work, but I think I can kill the "floating" look.
It was even worse before I put the dogs tail an part of his hip "behind" the sign.
Here are a couple before and afters:
I think if I let some more of the shadows come through the cloud layer, it might make the dog look a little more anchored. The contact shadows are probably key.