This weekend I reached 50 with my siren, after finishing the main campaign and all the optional missions I could, plus all of the current DLCs, in regular mode, then the first two DLCs (Captain Scarlett and Mister Torgue) in True Vault Hunter Mode, and finally powering through a second play of the main campaign in TVHM. I am now at the last mission, the assault on Hero's Pass and the subsequent battle with both Handsome Jack and The Warrior; when those are complete, if I understand things correctly, the game will reset (again) so that all areas are level 50 and the game is pretty much "finished" except for the boss raids and any loot farming you might want to do.
I'll tell you this: although it's not the hardest thing I've done in the game, getting through Fyrestone and particularly the Hyperion Info Stockade is no cakewalk at level 50 in TVHM. Saturn will mess you up, and even if he doesn't, those multiple Badass Constructor 2.0s (yes, there are multiples) sure as heck will. Make sure you have a corrosive bazooka on hand.
So... one story mission left; it's a bit of a wistful moment for me. With some teammates it would be fun to go back and do all those optional missions scattered across the landscape in TVHM at level cap, but until and unless sirfox and jbarrett get their vault hunters up to 50, it leaves me little to do but wait for the next DLC. I'm not about to go wandering around trying to solo raid bosses (there are those who can and do, I'm not of the mindset), although I might go and farm some landscape bosses for particular items. I could also go back and finish Sir Hammerlock's Big Game Hunt in TVHM but... meh. That was acceptable in regular mode when I was way OP for it... doing in on level just doesn't seem like it would be much fun.
I could start another character of course, but right now I'm just not interested in any of the available options. The mechromancer would be my next choice, but her My Little Pony skill trees are a shade too twee and put me off. The commando, the gunzerker, and the assassin just hold no interest for me. Supposedly a new character class is in the works, presumably to come with the next round of DLC, but until I see what (and who) the character is, there's nothing to do but wait for that, as well.
Oh well! I did get a copy of the original Borderlands and got my feet wet taking Mordecai through that, so it's an option if I get too jonesing too much for a game. Meanwhile... I guess I'll use the time to draw instead!