Mate, I support Newcastle Utd... I'm like a glutton for punishment haha!
I generally do some of the bounties with all three characters as well as the nightfalls. I'll do the Raids on occasion whenever they're happening. It does get stale, admittedly, but I only keep playing because of the desire to level stuff up (otherwise I wouldn't be on).
I'm disappointed that Bungie have made the decision not to include a Raid in the HoW but something fresh may just bring players back and keep the current ones playing (depending how well the Arena is received).
I'm still looking forward to the DLC though. Will be nice to upgrade stuff like Fatebringer etc! At least they won't be making such weapons obsolete...
I guess time will tell.