Typically I press open. There are times when I don't, like curved pieces, but if I can I press open.
I like just having one rule, when you press to the side there are a kazillion different addendum to "press to the dark side" unless this happens or that happens, or you alternate, or whatever. Plus I simply don't like the look of a 1/4" of three layers of white next to a piece that only has one layer.
In this case, I would indeed try the swirl thing if pressing open didn't work.
I believe pressing open requires the use of pins. When you do press to the sides you can nest them together by the lumps. I see people who do wonderful things without the use of pins, for me, I can't do it without the pins!