So, my optimizations are about connector pinning, and probably some of my personal preference (not all of them are necessarily better, just more like what I would experiment with next).
If you're willing to swap the ins and the outs, and rotate a couple of components, your ground plane can be contiguous across the middle of the board and you could arguably turn this into a 1 sided PCB, especially if you move the GND pin to the center. You'd end up rotating C2 180* and routing the out1 signal along the outside of the board. On the other half of the circuit, you'd rotate C4 180* and C3 180*. I personally would probably rotate R1 and R3 90 degrees as well just for cleaner signal flow, so from the input pin it goes in a straight line through R1, and onto the now bottom side of C2 and R2. Then the signal would proceed out the top of R2 and across the top of C1 and into the input pin. By doing this you also provide a clean signal path out of Pin1 of C2 toward the output pin since R1 is now rotated out of the escape path.
If you're willing to separate power VCC/power Ground off to a separate 2 pin connector on the right hand side of the board then you can eliminate the VCC trace around the edge of the board and fill the entire thing with GND. You'll still want to leave a signal GND over with the signal ins and out. This would help isolate any power supply noise from the signal traces since the signal ground path into the opamp would be largely away from the signals.
And one final suggestion you can definitely take or leave since I'm not sure if it's better in this case or not.... I've always found hooking something like this up is easier if each signal and each power pin has a dedicated ground pin. I personally would likely use a 2x4 header for this with each signal paired with a ground next to it, but I also tend to use smaller header pad sizes and tighter fill clearances so that my ground can get around the signal pins in a header - and I'm not saying this is a good thing, just a different thing. Another possible option would be to use two 2x2 headers separated with enough clearance that the ground can escape. If you're using 0.1 pitch headers, it's useful for the separation to be exactly 0.2" pin to pin so that you could span a 2x5 connector across them - I guess that applies no matter what the pitch, of course with different spacing to match the pitch. Of course another option (other than to leave it as it is) to add more pins in the same row, but that would quickly exceed your board size.