Now understand I have never made it over level 40*.

But I've always been worried about my level as compared to the number of quests there are. I don't want to level up to... say level 60, and then have nothing else left in the game to do. As far as I know, the actual questlines are as follows:

-The MainQuest
-The Companions
-The Thieve's Guild
-The College of Winterhold
-The Dark Brotherhood
-The Daedra Quests
-The Civil War

It's a decent amount I guess. Of course you got all those other side-quests to do, but I tend to forget about them rather easily. I play on Adept mostly, but switch to Apprentice and very rarely Novice when I need to (damn Spriggans). After completing each of the questlines, what would you predict my level to be? Do you think I'd have a 'maxed' character (I think level 81 is maxed) by the time I finish the game?

I got to like 32 just doing up to Dragon Rising on the MQ, and collecting all of the Daedric Items. I retired her after doing that.

I wouldn't recommend doing this because all of the "main" quests tend to be some of the least fullfilling and boring quests to do. But doing all of those, I doubt you'd hit 81 because you can do a lot of those quests like DB and TG without using much stealth skills.

I found lot of cool places when I was in cities just doing "Fus" not hitting anyone and Couriers giving me notes pointing me to "sources of power".