This may be completely stylistic preference, but you got a heck of a vignette going on in all the shots. I only mention this not because a strong vignette is a bad thing, it's just that the edges end up being very contrasty in these shots, my eye doesn't have a good "latching" point.
I think that last shot is strong. I'd love to see it as a big print. The color of the bench draws the eye very strongly, and the tones of the path and trees are excellent.
I'd think the photo of the giraffes would be much stronger cropped in somewhere. The high contrast highlights the pattern on their coats, but the centered composition is static. This is a shot by Andrew Zuckerman:

Of the opposite end of the giraffe

, but the arrangement of the animal's form compared to the frame is something to consider.
I think you've got a good style going, though. I don't think I've personally ever used the presets on Lightroom, I just edit based on what I feel my eye is visually pulling me towards. I think that sort of free manipulation is a good key to finding a visual language that fits your style.