I like the look of the first one. but the one thing that is overlooked in most of your pictures is composition.
It looks to me like you have alot of space above the heads in the 3rd and 4th.
I would advise you to look into the rule of thirds and put it into practice.
I would just work on your framing.
Make sure there is even space on each side of the picture.
It is best to leave more space on the sides of the people allowing for you to crop in and give even space to the top sides and bottom. other than that I would possibly use a diffusion filter on the close ups portraits.
The 1st picture is my favorite. The only thing i would have done different. I would have taken either a longer exposure or used a higher ISO to pickup a tad bit more light in the background. It looks good though. Keep on working at it.