A guy hanging upside down a tree and a girl leans into give him a peck on the lips: Blood rushing to the head, branch cutting into legs, doesn't sound the most comfortable
Two couple hanging on to a handful of strings of balloons(flying above air as they give a kiss to each other): Kind of awkward but it could work if she lets go of the balloons as they kiss. It would be interesting from a cinematic stand point but maybe not so much written of course if you are a good writer you could make it work.
kissing in the fog as it hazes around them: This could be good if you really get the description of the feeling of the cool fog on the skin etc
tiny couple who sitting on a flower as the garden that surrounds them blooms with flower: This one is pretty specific isn't it?

I'd say this is the most cliched and in my opinion has been way over done with the flowers blooming around fairies
A good luck peck on the cheek during a war type of scene: A classic of course but it could do well if you put some sort of spin on it
in a dreary forest kind of path kissing as trees and branches bend forward to enclose them:the same remarks as the fairy one
kissing on a dock in a pond while fishing for fish: or fishing for something else...but seriously, this one, like a lot of the things you came up with are very specific. If really depends on the characters and how it fits with their personalities/situation/status.
a kiss of resurection where a person kisses the dead and suddenly be able to awaken: This idea kinda always freaked me out. Why would you kiss a dead person?
I guess what I'm really trying to say is that while none of them are bad ideas, and are certainly better than the cliched ones, they seem very specific. I would focus more on the physical sensations and emotion rather then the situation that they find themselves in.