My two copper:
If renown must be linked to loot rather than favour for some reason, what about a very small, fixed amount of renown to EVERYONE in a group every time a bag drops - so there's no worries about having to pick bags up, and after all bags are available to everyone in a group, there's no ninja looting of them anyway, so bags are already 'party-wide'.
If the amount is small (and I mean 1 or 2 points) then you don't even need to adjust the bag drop rates, and people don't need to go out of their way to pick them up - the mere fact that bags have dropped ups the renown. the amount earned per adventure could be tallied, awarded and displayed ONLY on completion - so no farming mobs for drops. That does leave something needing working out for wilderness areas, but I think would kill a number of birds with one stone:
- No renown without quest completions
- Reduced farming if bag drop rates are the same for everything (you might still farm quests with lots of mobs for more bags, but you do have to complete the quest!)
- No need to pick up bags.
- XP and renown (which is only Guild XP after all) earned on the quest visible from a single key press.
- Renown builds in PuGs equally across the board regardless of the zerg speed or bag-grabbyness of the puggers.
Things to watch out for:
- Wilderness areas & bag drops - what will happen here? Would it be rares + chests only since you get XP for them specifically? In which case presumably you could link it to discovery areas and slayer awards too, which might be nice. I love the idea of seeing dozens of people from the same guild forming up outside Searing Heights in order to form mini-posse's and go clear the zone, and getting renown for it ("hurrah for the [guild name]!" say the local populace. "They've prevented the drow from overrunning the city! Hurrah!" etc etc)
- Quest Difficulty modifiers - will they intentionally or unintentionally affect the renown awarded?
Things to watch out for on renown system generally:
- Non-Guild aligned players - will they still earn renown somehow and what do they get if they do? Anything? nothing? is it stored up for later or lost?
- Lag caused by additional calculations during quests.
or you could just link it straight to XP and/or favour and have done with it - you want to farm renown? Get everyone in your guild to level. A lot. Kinda encourages mahoooosive guilds and punishes small ones though I guess.