I assume you're asking about mulch for the beds. Gravel and wood chips both have up-sides and down-sides.

Wood chips will decompose and add nutrients to the soil. Grasses, of course, generally don't need a lot of nutrients, but they do need some, and hardwood chips decompose slowly, adding nutrients slowly. You'll need to replenish regularly.

Gravel, especially if it's freely acquired on your property, is a more permanent weed blocker, and will still let sufficient water through. It probably should all be close to the same size and color, so you may have to do some sifting. A frame covered with hardware fabric, in 1/2" or 3/8" mesh, will give you a good size.

Snakes won't necessarily be more attracted to either. Rattlesnakes will look for sun-warmed spots in cool weather, but Copperheads tend to avoid open areas, and are attracted to lots of moisture. Be careful when gathering gravel from your creeks. Undergrowth beside creeks would be a good spot for Copperheads. Make lots of noise and use a 6' long bamboo switch to rustle the growth. Copperheads generally will steer clear of you.

Thanks again, Donn! I think I'm going with the gravel. As far as getting it, we'll use the tractor, if the creeks ever go down from all the rain we've had. My in laws keep telling me not to use the rocks because the copperheads will lay in them. But at least we would be able to see them easier on the light colored rocks versus the reddish wood mulch. I chose to do the grasses to avoid have a lot of cover for the snakes to hide under.