I think on all of them, the background could be utilized a little better. Most of the shots have the subject centered, and the camera is more or less straight onto the subject and the background. Your last shot does a good job trying to capture the columns going back, but if we could see more of the columns fading into the background, it would add a lot more depth to the photo.
For the brick ones, if you took the shot from a greater angle, you'd get the foreground blur of the bricks as well as the background blur as they fade off into the distance. This would also give you a different pose or position to work with.
Also, there are no horizons on any of the shots and the lighting is a little flat. Since you are working with a point and shoot camera, try using some type of reflector to add some direction to your lighting. Or maybe shoot out in the sun instead of the shade and use a reflector for fill. Shooting in the shade is the "safe" way of avoiding harsh shadows, but when everything is the same tone, it can detract from the photo.
I'm just getting started with these portraits as well. Good job though, keep at it! You can still take great photos with a point and shoot. Focus now on improving your composition and use of ambient light.