Well, first off you'll be dramatically increasing advancement unless you cut the xp for monsters and traps down.
Here's what I do... First, all standard xp awards are cut in half.
Then, at the end of each session, each pc gets a chance to make a case for xp in each of four rp categories: race, class, alignment, and personal. Each category is worth 25/level xp. I purposely leave the exact requirements somewhat vague and easy to achieve; I prefer to let every pc get every award if they can come up with something.
Using your class or race abilities doesn't count (a bard can't claim class xp for using bardic music to help the party, but if she sings in the inn for her supper she can).
Lemme give a couple of examples here for clairity: let's start with a 1st-level LG human cleric.
At the end of the session, our cleric mulls over his actions in the session. For class, he made a point of saying grace before the party ate at the inn. For race, he made a point of hanging out with other humans, also at the inn, and buddied up to the human innkeeper. For alignment, he rushed to aid a complete stranger being attacked by wolves and later kept his word to someone even when it was inconvenient. For personal, he started a romance with someone.
You can't call the same thing in more than one category, either; so if the cleric tried to call making friends with the innkeeper as a personal thing or a racial thing, I'd give it to him, but not for both.
Hope this helps.