BB Dazza: from personal experience, and watching and training with others, the close curl grip BB row is very productive. Probably the best version for most guy's (remembering also, that no one exercise will work equally well for everyone). Do what ever hand grip works for you. But the curl grip tends to hit most of the upper back/lats well. With the affect of adding mass and strength quite. Keep the elbows as close to the sides as possible, don't let them act as "wings".
With the DB row, close to the body, the hammer grip is used. Also an effective movement for back/lat development. Personal view (of whatever value); would always choose the BB version, of any rowing style, over the DB version. Only exception would be a DB row, where the elbows are way out and stay in line with the should girdle through the whole arc of the exercise. This will hit the rear delts strongly, as well as the traps. Just think of them as a rear DB raise, with a 90 degree bend at the elbow. And remembering to pull, or lead, with the elbow. And you get to use much more weight that a regular rear raise. This theory can be allied for lateral head delts also, with some other exercises..DB or BB.
BB'ers will use the hook/thumbless/false grip, quite a bit. BB'ing does not require a huge amount of weight in a rowing exercise, or pulldowns/chin's for that matter. The "hook" idea is to take the actually focus off the grip and on to the pull motion. Most BB'er will have too tight (and focuse) a thumb grip on most exercises, including benches/presses. Using a thumbless grip on benches is fairly standard for a lot of guy's. If wanting a thumb around the bar grip, than may be better served with a lighter, less tense grip. Good Luck.