Position is all important; the two saplings in the foreground really detract from the waterfall. Technically, I would suggest a little more saturation and about 1/2 stop lighter.
#2 (Doug Firs): I suggest cropping the trunk out of the RH side of the frame; not really sure what the subject is on this one.
#3 (Interior Bridge): Neat idea, and another which would have really been nice to have the tripod for (I feel your pain!). Only suggestion on this one would have been to wait until the people were clear. It would have also worked nicely as an HDR Merge, if you had been able to take a few more frames, and given a better interior exposure and a less blown view through the exit.
#4 (2nd waterfall): Again 1/2 - 1 stop lighter and some saturation would really help.
#5 (Bridge, BW): Nice, perhaps just a tad more contrast.
#6 (Bridge exterior): I really like this one. If you wanted to really work it, perhaps tease the levels a little and lighten up some of the darkest shadows just a bit. You could also clone out the electrical box below the entrance, but that's just being nitpicky.
The last one doesn't show for me.