About 7 months, level 53, 302 hours. Starting my second character in 2 weeks time. Only because I was forced to do so though, I prefer the one playthrough and living with my decisions.
I started with a 2H Nord at launch and it lasted a few weeks but I didn't really like the direction it was going.
I tried out a Khajiit thief but the tail and whisker clipping drove me insane so I started a Nord Paladin. His beard clipped as well and thus drove me insane a second time.
I now play a Bosmer "Bow-Mage" and I don't plan on playing another character for a long time, currently lvl 39.
I usually stick with one character for a very long time as my main guy. Typically my Khajiit rogue.
If I have a playstyle I feel like playing one day I'll make a new character just for that playstyle and RP alone, they usually don't get too high level, but it depends on how fun I deem the RP.
I'm addicted to the character creator so I start new characters quite often. I have so many characters. But no pun intended, I can't play a character unless his face has character. A lot of times I'll make a guy and play as him for a while and realize that I hate his face. Out of the eight or nine characters I've made, I'm only really dedicated to two of them...
My first character ended up at level 44 IIRC before I retired it. Earlier today I retired a level 36 character. However, I have also retired characters in the early 20s. This is not counting some of the characters that never made it past level 7 because I didn't like playing as them.
I find I often get bored with my characters when they're somewhere in their 30s or 40s. So I go back and start a new one. Unfortunately, by now, I'm having a hard time thinking of a build I would actually stick to that I haven't already done or doesn't seem pointless.
On my first Redguard I got to level 36 then didn't like his playing style restarted made a Wood-elf level 65 then restarted to my final Redguard who's based on magic/sneak/melee (bit of range) currently level 12.
250 hours on my first character. My second has just over 300 hours now. I won't be starting a third, not for a while at least. Playing Oblivion at the moment. Won't go back to Skyrim until after Dawnguard is out.
I'm a min/max type of person so as soon as I realized I'd misspent a point I restarted. I had around 20 characters started within the first 24 hours of buying the game. I've still never gotten past level 40 on any character.
Played 200 hours oon first up to lvl 60. A jack-of-all-trades Breton. 60 Hours on my Nord/Lycan warrior lvl 46 Cuurently on my 3rd character, a mage that I enjoy playing with and RPing.
It really depends on how do you play/like that character. Do you RP?
Level 57 for me and over 200 hours on one character before I started another. 10 or 15 hours in and I'm still struggling to stick with the new one. However, I prefer having a female Nord on my screen now, as opposed to my original Male Redguard.
I've got my lvl 28 High Elf Battle mage, and lvl 12 Wood Elf Illusionist Nightblade. I'm planning on creating another character but not until at least those two get into the 30s.
I've retired about 10 characters and the highest one was 43rd level. Each done does a few factions, based on the type of character they are, they may or may not do the main quests, and then they are retire.
I switched when I realized that the character that I had meant to be a mage was actually an Archer. Almost level 50, but not quite. I have not gotten a single character to level 50. I tap out at 45 most of the time.
Aside from a brief play session with someone else's Skyrim (ere I got my own), I'm still on my first character, a female dark elf who likes setting things on fire.