My gaming sessions tend to go for 6 to 8 hours, so since RT I have been giving 100xp per hour. I'm not a huge fan of bonus XP, as it can lead to the more "active" (ie, verbose) PC's getting far ahead xp wise than the more "quiet" (ie, still new to RP'ing compared to the rest of us that have been doing it for 25 years now) PC's.
My group also has replacement characters comming in at the same XP total as everyone else that survived. It works well for us. It can encourage great heroism and good action scenes to know that you won't loose thousands of XP if your character bites the big one.
Also not a big fan of a big lump-sum XP bonus at the end of a story arc / adventure. I much prefer those rewards to be in-game things. Be it the colonel of the regiment stopping by to award a Medallion Crimson to the brave sniper that fought on against the ork after being critically injured, or liberating a Chalice class battle-cruiser for their dynasty from the icy space hulk it was trapped in.