So I get that you can replay a scenario with the same character over and over again to 'mine' card upgrades but you don't get other bonuses for it. No feats, no extra scenario rewards. However, what about playing it with new characters?
Here's the scenario I found myself in. 2 of my friends and I started on season 4. We played 3 games, myself with Talitha. Then another friend joined (playing Adowyn), and we finished out the teir (the four of us played games 4-1D and 4-1E) together, beating it by the skin of our teeth.
Now, I know that my friend who joined us late can play out of tier and eventually catch up, but I also know that there are bonuses for completing every scenario in a season. So I decided to play through season 4-1A, B, and C with him so that he could get caught up (and playing solo is no fun!) I played a new character (Verril), he played Adowyn. Do I get credit (skill and power feats) and rewards for beating that/those scenarios as my new character? I mean, I am playing it again, but not with the same card character.
This is where the card guild and the roleplaying guild are fairly different. In the PFS roleplaying guild, a player can not replay a scenario, unless the scenario is listed as replayable (and a few other ways), but the default is that you play each scenario once as a player.
In the card guild, you can play each scenario multiple times. Each character can only earn the reward from a scenario once (remember, deck upgrades aren't a reward, since they happen whether you win or lose). The multi-table interactive specials, as parody noted, are the exception. The default there is each player can only play the card guild side once.