I always want more from my character, so I start over. After 2000 hours of playing Skyrim, finishing the main quest only once, and using a total of two races (Khajit and Wood Elf), I find myself working the quests too fast losing the essence of slow playing and role playing. For example, as soon as I finish The Golden Claw and Bleak Falls Barrow, I make my way to Ivarstead. From there I visit the Greybeards, get the next task from them, and then head to Riften. I'm a thief in this build and will eventually get to the Dark Brotherhood. I follow this approach as it is a role playing experience. I don't go in quest order, nor do I fast travel as it takes away from some really good encounters.
For games like Skyrim, I like to explore and take each quest as an overall, but individual experience. For instance, Honningbrew Mead I would complete that quest alone with my bow as it gives me a good opportunity to sneak and get some good kill shots.
I don't know if I will reach 80th level, and I've only used the Legendary option one time. For some skills, I don't see the need to do so. However, Legendary gives you the ability to switch your characters direction - a thief transforms into a coded Warrior, etc.
And with the many builds out there on the Internet, you can guarantee that using Legendary is much better than having to start over.
