Hmm with the vines, what I would typically do is model  the vine, itself,  as normal but the leaves would be transmapped to flat squares that are only one poly each. This signifigantly lowers your poly count.

This is also nice if you want to have different leaf shapes and colors. You can create material zones of 3-5 (or whatever) for the leaves and have that many different leaf types of varying shape and color and it doesn't effect your overall polycount. You could also feasable get away with doing the grapes, themselves, this way if you aren't relying on a closeup of the vines. The leaves would be fine on closeups though since leaves are flat anyhow.