Gamemasters:

If you prep encounters for players, do you consider what the players want? What the characters want? Say you have a power-gamer who loves anything that makes his/her PC more amazing. Do you think,

"Now, my power-gamer's going to want a new (fill-in-the-blank item) so I'll make sure the (fill-in-the-blank foe) has that on-hand. Spoils of war!"

Or say you have a player who loves puzzles. Do you think,

"Hmm. My puzzler will be looking for clues at this next location, so I'll make sure to add some red herrings and a piece of good evidence."

What about the character? If you have a PC with a serious fetish for combat do you think,

"Uh oh, Ralgron's twitching again. Time to throw a little combat op at the party."

What about a mage/scientist type who is always searching for new text? Do you think,

"Okay, Sherlock just survived a rough combat. Time to produce some arcane documents requiring careful examination."

For GMs who don't prep and run mainly on improv, do you keep player or PC wants in mind, or is it more of an obstacle? Am I the only GM that considers this? Which seems more important in your opinion: player wants or the desires of the characters? Both? Neither?

Finally; what about the Gamemaster? Is the adventure the GM's "baby"? Should the GM design encounters based almost completely on what they find entertaining? Have you ever done that and if so, was it personally rewarding? Are there moments within our hobby where GM fun & player fun are mutually-exclusive?

All comments are appreciated and I'm interested in the player perspective as well.