IMC, I impose downtime on the PCs every now and again. While the world is an exciting place, full of adventure and intrigue, it just is not conceivable that people will live everyday of their entire lives persuing villians and completing epic quests. Usually after three or four related adventures, some conclusion is reached and the PCs return to their "normal" lives. I let the players come up with what their character is going to be doing during this time and if it is relevant to their class(es) they may get a little bit of experience, but not much. I use this time for several purposes:
1) It allows the PCs to "grow into" their new stations in life.
2) It gives the PCs time to craft items, buy/sell/trade equipment and treasure.
3) It gives the PCs time to establish ties outside of the party without dedicating too much "table time" to unexciting role-playing(we don't get to play that often, so we like to concentrate on actual adventuring...not on the every day lives of the PCs).
4) I assume that most PCs are not all that interested in being professional adventurers for all their lives. They would generally try to establish some modicum of "normal life" between adventures only to be forced back into adventuring by fate(like what happened in the movie Tombstone...the Erp brothers tried to become business men before being forced to take up the gun to destroy the gang of villians).
For instance, in one series of adventures, the PCs went from 1st to 4th level by destroying a goblin raiding operation in their homeland, rescuing some important NPC's family members who the goblins took as slaves and slaying the goblin warchief who initiated and lead the operation. This took like 6 game sessions and established the PCs as important people within their home village. The local lord took them in has his personal vassels, gave them modest homes to live in and assigned them positions within his lands. Then I told the players that there would be some "downtime" that could be a number of years and asked them what they do. Some of the PCs accepted their positions others left to persue other careers. I then allowed five years to pass. Then I used the local lord as a convenient adventure hook to get the PCs all back together and off on a new series of adventures.