I like those fabrics and think both would work well for 4PP. The finished look would be less "in your face" and not so vivid and garish as some 4PPs, OBW, etc. can become. You'd get a softer more subtler look. The 2nd might give you a lacy effect with the design already there.
Yes there's open space, but don't let that scare you away. The open space can help to give your eyes a bit of a break, rather than so much going on. That being said, there's two things I'd take into consideration .... if doing 4PP, consider the block size ... don't get it too small, or yes, your blocks will only be he background. The other consideration might be to make a OBW ... then the plainer blocks can be worked into the end layout.
Here's a OBW that I did ... many would have said NO to the fabric, because there was too much background. And yet it worked just find (IMHO!)
http://www.quiltingboard.com/picture...i-t141548.html
I'll look forward to seeing your quilts with both of these fabrics!