The last crossing will be our view from the living room. So this bridge needs to "blend in" with the surroundings - so I would like to stay away from drums, culverts, concrete etc.
punkrockpilot- Don't know how good a stone mason you are, but if you went with a native local stone facia, it probably wouldn't look to out of place. A culvert with a flow adjuster could give you a swiming pond right there in view of your front room. You might be able to get a nice water fall effect from the overflow. Heck, you might even be able to get hydroelectric out of the thing.
There you go pard- you got the bridge, the swiming pond, the waterfall, the electric company, all right there outside your front room window.
Would a diving board look to far out of place ?