When you have gaming sessions that turn out to be role-play focused and not combat, do you award experience for those games?  If so, how much do you reward, or do you have some formula you apply to those sessions? 

I personally go by a "seems about right" approach rather than a hard rule, because A: I want to have control of when people level up, and B: I don't want to spend much time working out the xp for fiddly things.

So what I do is I take any encounter where they expended resource or actually had to try, IE the main ones, and I work out the XP for them. I use this as a basis for when they are getting close to the xp threshold. Then once they're fairly close (roughly one combat-oriented session away) I aim to engineer a repreive where they can level up. If they have done lots of roleplay, this will come sooner, and if they have just been doing combat, then I will wait until their xp is closer to the threshold.

Milestone XP. Rather than fiddling with numbers after a combat and wondering, as you are now, how to credit not combat related encounters, it’s much simpler to have characters level up after reaching certain points in the game. Some examples are: DDAL awards a level every 8 hours of gameplay (IIRC). Other organized RPG’s I’ve participated award a level after 3 sessions, no matter the individual session lengths. In my home game, we level when we complete a major quest/task that drives the over-arching plot of the campaign forward—generally following the roleplay, investigation, and smaller skirmishes and encounters that culminate in a climactic BBEG defeat; it’s pretty conveniently self-apparent when it’s time, actually. 

I award 25-50 XP/skill check, and 50 XP for each instance of RP. It’s certainly possible for a PC to earn several hundred XP per session that way in addition to any combat they may engage in. I also aware XP for overcoming any challenges such as traps, puzzles, or NPCs. Talking or stealthing your way past a guard earns as much XP as killing them would in my games. It doesn’t matter how the challenge is overcome, just that it is.

So, the typical session I have been running for the last year generates about 1500 xp per player, +/-800.

anpure role player session would get around the same amount, assuming it advances the story. If it is just “color”, then it really varies by how much 

growth or how much it will contribute to the PC’s future role play (and since I use those sessions to set up little things in the future as call backs, I want that!)

Usually, I just eyeball it. But rule of thumb, I figure about how much xp they'd get for a combat and give them about that much. It's a particularly good way of stopping murder-hoboing when the players realize that people they talk to aren't just xp pinatas that need to be broken open to get to the good stuff.

It is usually best to stick to your judgement, because rules like that are relative to the plot and party.

For what it is worth, I keep tick marks next to a player's name on my HP tally sheet for role playing.  Anything that is really fun or exciting gets a tick mark.  (Good battle tactics, skilled negotiation, etc also get a tick mark).  When we finish a session, I total the XP for killed monsters (usually from a book) + completed quests or substantial pieces of quests (a number that feels correct to me) + number of tick marks multiplied by X.  The bonus XP is roughly 10-20% of the total XP.  Most players get 2-5 tick marks per session.  

Quote from Velstitzen >>

For what it is worth, I keep tick marks next to a player's name on my HP tally sheet for role playing.  Anything that is really fun or exciting gets a tick mark.  (Good battle tactics, skilled negotiation, etc also get a tick mark).  When we finish a session, I total the XP for killed monsters (usually from a book) + completed quests or substantial pieces of quests (a number that feels correct to me) + number of tick marks multiplied by X.  The bonus XP is roughly 10-20% of the total XP.  Most players get 2-5 tick marks per session.  

 O WOW I love that!!! I am so using that rn!