well.. its my opinion (which carries very little weight compared to the other great players on this site) that Rooks gain in power in the end game when most pieces have been cleared from the board and they can control an entire rank and column. Also two rooks linked together have the ability to guard one another which is something that only knights can do as well. I tend to keep my rooks on the back line as they are excellent guardsmen against promotion and back rank checkmates. Hope this helps but prolly didn't contain any information you didn't already know ;)
Rooks or Books???

After the opening, you should have them in d1 and e1, to try to control the center.
Then, when you have a good semi-open file (with only an ennemy pawn), you should have them both in this open file.
The dream of rooks is to be together in the 7th rank.
Rooks are best when there are not very many pieces on the board. At the start of the game, you're right - they tend to get blocked in by their own pieces. Hang on to them though - they're very powerful in the endgame!
But where do you put them???
Generally, they're better in the center of the board (on d1 and e1 as white, or d8 and e8 as black).
Is it really that important to have them
Yes! If your opponent has them and you don't, you're in trouble!
because i rarely use them in a game.
Hmm... so use them more
Okay now this is a tricky one for me... Where exactly are the rooks main purpose to be at? There are so many pawns in the way, how do you get them out there? Ive heard that its best to get them together or lined up and are used for great attacking purposes. But where do you put them??? Is it really that important to have them because i rarely use them in a game. Only if i can get them exposed. What am i missing here???