Apart from few designs with initials SF (entries #109, #110 and #111), there are few variationd on basicaly one design, that is a bit out of the box in regards to your design brief, but I thought you might consider a bit softer/flexible design, more apealing to your clients (entries #112, #113, #114 and #115).
Hope you'll like some of them, and if you have some suggestions for improvement, feel free to jump in with ideas! Thank you!