In two of the games with the Black pieces I faced sidelines in the Ruy Lopez that I haven't gotten around to studying yet. In one of the games, I managed to come up with the plan recommended by the books and in one I didn't, but in both games I wound with two bishops against two knights as compensation for a damaged pawn structure.
Bishops v. Knights
Novice chess players are usually taught that knights and bishops are equally strong pieces so that trading one for another is an even swap. However, I have run across many high school players who view the knight as much more dangerous. I suspect that this is because the knight's move is more difficult to visualize and they tend to show up on unexpected squares to deliver nasty forks. Many young players will happily trade their bishops for their opponents knights at the first opportunity.
At higher levels, bishops are thought to be slightly stronger pieces, although the features of any given position determine which one is superior. The bishop does well in positions where it has open diagonals upon which to operate. In a position blocked with pawns, knight's ability to leap over pieces and pawns may give it the advantage. A knight is happiest when it has a secure outpost where it is defended by a pawn. (One thing to keep in mind is that blocked positions often open up, while the opposite rarely occurs). In an ending where there are pawns on both sides of the board, the bishop tends to dominate due to it's ability to operate at long range, but when the action is confined to one side, the knight's ability to attack squares of both colors may be key. Queen's and knights tend to work well together while the bishop would prefer to be paired with a rook.
One of the things that makes a bishop very handy in an ending is its superior ability to make a waiting move. Whenever a knight moves, it no longer protects or attacks any of the pawns it protected or attacked before it moved. If the knight is preventing an opponent's king from advancing to a more favorable square, it won't be after it moves. When a bishop moves along a diagonal, on the other hand, it still can still cover squares on that diagonal.
The position I reached in the 1st round of the Illinois Open illustrates some of bishop's advantages. Although Whites is down a pawn, one might think at first glance that his nicely centralized king and superior pawn structure might give him some chances to draw. In fact, it is a pretty easy win for Black. There is no way for the White knight to get at any of the Black pawns, and the Black bishop easily forces the White pieces to give way. The game continued 42.Nb1 c5+ 43.Kc3 Kd5 44.Nd2 Be2! (Just in case the knight had any thoughts about heading over to the king side via f3 and h4) 45. Nb3 Kc6 46.Nc1 Bf1 47. Nb3 Kb5 and the White a-pawn fell.
In the 4th round, the bishops proved their superiority in the middle game. My opponent played the Exchange Variation of the Ruy Lopez but the long distance power of my bishops prevented his knights from ever getting passed the third rank. When knights are forced to defend each other it is usually a sign of a passive position. The game finished 33.a3 Be5+ 34.Ka2 Kc3 35.Rd1 Re3 36.Rf2 Rd8 37.f4 Bxd3 38 fxg5 Bb1+ 39.Kxb1 Rxd1 0-1.