Couldnt you just create a circular fillet ?

Make the leg intersect the body, select both the body and the leg and then Edit NURBS>Surface Fillet>Circular Fillet. Adjust the fillet diameters in the Attribs to get the size you want. Then copy out the curves of the isoparms for the fillet, and also for the leg (U or V running ones, not both). Then delete the leg and fillet surfaces and loft the curves you've made to create a leg with a smooth join to the body.

I also have had nothing but grief with booleans and the surfaces they create, I only use them now when I can think of no other way of achieving what I want.