I often get out of fights with random characters and creatures I meet along the way by running away. It works most of the time, especially with giants, spiders, and even on occasion, with tigers and bears. It's pointless trying to run away from wolves though.
When I do the 7 Thousand Steps, I avoid the snow troll by going down the side of the mountain just before the place where he appears and rejoining the path a bit farther along.
Is this cowardly do you think?
My thought is that they are only protecting their territory, into which I'm intruding, so why should I kill them because they are doing what comes naturally?
Do you ever just run for it?

I run from Horkers, that is about it. Anything else I just kill because I have a chest for practically everything, and like to hoard.

http://www.youtube.com/watch?v=Vcx6UbMCtfI

My nord would say it's cowardly to run from battle but that doesn't mean you should run towards it and start fights. For example if a bear is nearby and growling but doesn't attack then i'll leave it be as it's just warning me not to invade its personal space...if the bear attacks then i will charge back at it with my axe as it's invading my personal space and all intruders get put down

Only cowards flee battles.
Those creatures are not strong enough to hold their territory.

I would if they'd let me. In Fallout it's so much easier to avoid battles despite most enemies using guns. In Skyrim the damn enemy will follow you to the other side of the world if you just run.

I don't really mind hacking my way through everything but I'd like there be possibilities to avoid battles. For example if you use Thuum on normal bandits they would run away and thus either let you butcher them or just run past them.
Though sometimes using Fus Ro Dah gives you enough time to flee. My Altmer characters in particular try to spare their kin in battle.

If you avoid the snow troll early on in the game I dont think it's cowardly, more self presevation. I will avoid anything I dont think I can beat with a new character until such time they can defend themselves. Whatever gets you through a situation is the right choice, later on in your adventure things like snow trolls will run from you if you have the right spells and equipment.So dont let it bother you.

If you are playing a character that avoids initiating those encounters out of respect for those creatures, then no, it's not cowardly. Earlier in the game, my current character was forced to kill two giants because on each occasion they were hostile from another encounter and had her cornered. (Sometimes when giants get in fights with other creatures / people, they stay hostile on anything in a certain proximity. Bears will do the same.)

Now, though, she's made peace with what happened and lives between two giant camps. She respects the giants and disagrees with certain Jarls who think they need to be eliminated. She could kill them, but she chooses not to. She leaves them alone, they leave her alone, but she's been known to provide an assist if she hears a ruckus. (They rarely need her help, but she makes the effort anyway.)

Running away isn't cowardly in itself. The reasons for running away / avoiding encounters matter.