The trick with gluelines is preparation, preparation, preparation!!
If I wanted good gluelines all the time and I didn't have a drum sander. I would saw them myself then find a good woodworking shop who does have one then make friends! A drum sander is THE tool to prepare lams. Planer thicknessers are ok but they leave a washboarded surface and actually compress the fibers thus not really allowing a proper glue bond. Lams prepared with a drum sander will always be flawless. To make tapered lams just buy a set of 0.002 and 0.001 tapers from Binghams, put these on a simple sled with a butt end stop and put your lams on top, they will then be ground to perfectly match the base taper. Most wood bows like about 0.005 to 0.008 per running inch tapers. If they ask what grit you want them done with 60 grit is the one.