I've done pretty much all the quests in one playthrough or another. I'm currently doing a total completion one and will probably never be this thorough again.
I was appalled when I found out I had to desecrate the tomb to get a mosaic piece. I've never done it and was worried I wouldn't be able to get the Dalish agent because of it (still got him, thankfully).
I used cheat engine to get the shards because I lost patience finding them all but wanted the quests for the doors off my journal.
All the missions where you find a map and have to dig up a treasure drive me nuts.
Finding the chanter/spirit in the Hissing Wastes is causing me grief right now. At least that one doesn't show up on the journal.
I didn't even know about the bear in Emerald Graves, I usually clear everything out at once and then never return. This information is going to force me to revisit all the maps to check for quests now...