Running: Grass vs Trail vs Road

I generally run on the road (asphalt), because that's what's most convenient, and it is what I will be racing on.

Trails: Wish I could, but with several ankle sprains in my distant past and a few and knee surgeries in my recent past, the risk of injury on some tree root or rock is just too scary.

Grass:  Yes, when I can (normally for one of my slow to moderate runs per week).  I will also sometimes do a short run in just socks on asphalt.  Crazy, perhaps, but I like it and have done it for a long time (years, not months) and it doesn't seem to hurt me so long as I do it in moderation.

Track:  all speed work (which used to be once/week but recently is none since I'm recovering from near-injury) and some other runs (maybe 1 other time per week).  The track that I run on is annoyingly short (1/7 mile), but has the advantage of being a very good surface for running and indoors, so it has its attractions (especially in awful weather) despite the tediousness and sharp turns.

Well....usually mix it up all the time!!!

I am never really planned, but my favourite runs are beaches and really hillysome trails.....nothing beats the awesome amounts of oxygen and fresh air at those locations!

I experience knee pain every once in a while, mainly becuase of ashphalt.....so i try to stick to softer surfaces, but i feel faster on sidewalks n' roads.

You mean by spraining them? 

I do most of my runs on sidewalks. 

Almost all of my runs are on sidewalk/road.  About the only time I spend on trails is for races, and occasionally I can do a quick loop on a longer run.

The reasoning is availability.  I am not driving somewhere just for a training run.

I usually run on a nice trail beside where I live with a mix of asphalt and concrete.  3 times a week, 25-30k per week.  However, I tend to  run on the grass right beside the trail.  Especially the smooth newly paved grass without any holes.  I found that its better for my knees.

Between asphalt and concrete, I was told asphalt is better because its a little bit softer, I personally can't see a difference.

rubber covered indoor track is nice, but I enjoy outdoor atmosphere.

Im lucky in that I dont have to run on sidewalks or on roads with a lot of cars.  I live on a 2.5 mile dirt road so I mostly run laps on that.  The road has a nice big hill too.  I also have a hay field in front of my house and have a 3/4 mile loop so I use that for a couple weeks until the grass is too high.  There is also a high school gravel track a few miles away that I have also used to establish my 'standard' time and did my first couple of bricks.

My goal for next year is to work out a trail (1/2 mile loop) in the woods behind my house so I can run w/ my dogs w/out them having to be on the leash. 

So to answer your post, I prefer trails/dirt roads first, easier on the knees but still hard enough so racing on the road isnt that big of a change.  Grass is second (the dew in the morning makes my shoes too wet) and sidewalks/roads are my last preference. 

That's just beautiful...

I run on trails - I love it because there are big steep hills where I run and little winding ups and downs. It is always fun to jump over roots and rocks, and downed trees.

I run a little bit on the road and when I feel like being wild I run on the High School track - but not often. 90% of my running is on trails and I think it builds better endurance. I'm no expert but when I run a race (on asphalt) its cake compared to the woods.

...wow I can't spell