Kryssa, there really isn't a reason not to iron your seams open anymore, and although I've read the reason they were customarily ironed to one side, I don't recall what it was. A number of quilters iron their seams open because they prefer the absolutely flat look it provides. Some also believe free motion quilting is easier with flat seams. I believe there is some concern that seams are more likely to get skewed when ironed open, and that intersections of blocks require more special handling. I've done both, but I'm not experienced enough to have much of an opinion either way. When I have a little extra time, I'll try to find the sites where I originally got this information and post the links. Have fun!