I was level 71 when I finished the game.
My main character is at level 88, and I believe the game needs some new high-level enemies. Yes, you can still get waxed by deathclaws or a squad of Legendary Gunners, but odds are that after a certain level you're plodding through the Commonwealth like a divine juggernaut. In truth, I wish Bethesda had put a more stringent "soft cap" in place at level 50 or so. I'm not grinding up or anything - it's largely through building settlements after I'd completed all the quests.
Personally I hope to rectify this through content mods, namely something that randomly spawns unique enemies that periodically emerge from the Glowing Sea (e.g., named deathclaws, hordes of ghouls, etc.).
EDIT: I understand that there is a strong incentive to re-roll, but I've invested so much time and energy into this character and my settlements that I find myself wanting to stick with him in lieu of a new playthrough.
Level 65 after about 125 hours. Only got 6 bobble heads left to find, after that I'll probably retire that character. Kind of feel like I've done everything already, probably still a plethora of content left though.
Just hit 55 yesterday. Still have done only half the main story. Several areas I haven't yet. I think it's time to progress further in the main quest because there's nothing more than repeatable faction quests right now. I don't think I can get more until I advance.
But first, I must finish building my newest house in Sanctuary.
Level 26 now. At about level 18 I switched from Normal to Survival cause the game was too easy. Now the difficulty is just right.
I like to take it slow, scavenge every house and dead body and look in every corner of the location I'm in, although scavenging all junk for materials gets a little boring sometimes. I wish there were a button like: take all junk from this location you cleared: press R. That slow play and looting all I can find got me good armor and weapons, allowing me to keep up with enemies and also always have enough oil, screws, adhesive etc for fully modding all my weapons with Gun Nut and Science, Scrapper helps with that too.
I haven't taken Idiot savant yet but I'll guess I would like to, to power level though the game cause I just can wait to overpower my char and vats play style with Grim Reaper and Four leaf clover, sounds like almost unlimited action points. Still have to put 2 more points in luck and after that take those yummy perks. Then even legendarys will be piece of cake. Action boy lvl 2 just isn't enough sometimes when they mutate.
I'm up to level 31 playing on normal, but I'm also on my third restart!