Sorry, I got my terminology all mixed up.
The 'loft-like' surface is called a loft surface.
The blended surface is more like a 1 or 2 rail sweep... Create 1 or 2 'rail curves', and then only as many curves as necessary to define the section (tip: less is more.. too many xsec curves make for 'wavy' surfaces). These curves should be connected to the rail curve .
Then, create a new surface, select the 2 rail curves and hit 'ok'.. Then hit 'cross curves' and select the xsec curves, and complete the surface.
A good practice for the blended surface is to create the xsec curves using a datum normal to one of the rails (aka Radial Plane). After you have made the rail curves, create a new curve and designate it as planar. Open up the 'Refs' tab and press the arrow button next to the word Reference. Select one of the rail curves as the reference and it will change the plane type to 'Radial Plane'. You can adjust the length parameter to put the plane at the correct location along the rail. This ensures that the section curves that you are creating is always a true representation of the section (at least in relation to the rail curve that you are using).