There are a few side-quests that I like to play, but don't seem to have the option in the current play through. For example, when my Orc engages Noster Eagle Eye in Solitude, the only dialog options are for either giving him gold or asking whether or not he was really in the legion. There's nothing to start his quest and retrieve his missing item. Have the same problem with the smith in Windhelm - don't have the option to go retrieve that special sword.

PC is a female Orc, heavy armor, two-handed, and playing on Master difficulty. She's currently level 44. Any suggestions?

You may not receive certain favor quests while having the same type of favor active (i.e., you won't be asked to find an item in a dungeon for someone if someone else has asked you already and you accepted).

No kidding?! I didn't realize that's how it works. Seems like kind of a random limitation - what's doing a favor for someone in Windhelm got to do with doing a favor for someone in some other city? I wondered if it was a built-in prejudice against orcs or something.

Regardless, thanks, I'll have to review my journal. I do tend to accumulate miscellaneous quests. But in terms of quests that don't fall under the Miscellaneous category, I try to keep the list pretty clean, maybe just two or three quests currently.

The quests listed on the following wiki page must be done serially. I started the one for the ring of pure mixtures out of Dawnstar and have yet to return it. SInce I haven't returned it, the other quests aren't available (including the two that I mention specifically). This wiki page explains the organization and dependency between these quests:

http://www.uesp.net/wiki/Skyrim:Dungeon_Delving_%28Caves%29