Alright, here's my take. The first photo suffers from the fact that it really isn't that interesting of a perspective, and here's why. That is the same perspective one would get if they walked down the bridge themselves. I have often found that photos are much more interesting when shot from a perspective that the human eye doesn't normally see. That is what makes a person go "Whoaaaa..."
As for the second photo, I have spent a considerable amount of time in the everglades shooting photos of sunsets and I can tell you that the sky doesn't always cooperate. In your second photo, the sky really isn't offering you anything interesting, not your fault, just the way that particular night was. I think the photo itself would have worked better had the canal been calm. The waves disrupt the tranquility of the shot.
In closing, you seem to have the concept down. Your photos are technically well done. It just appears as though nature wasn't cooperating with you. A different perspective in the first one will bring it to life. Post your next shots, and stay well :thumbup: