As a level 50, you could solo the first 3 without too much of an issue. After that you start getting into things like Aurum Vale, and U'Ghamaro Mines where a party is required. You could solo 2/4 of the Double Dragoon quests.

For the Stollenwurm in Fatal Seduction, we rocked it with a party of 8 Dragoons, so I didn't bother to post a strat. He definitely requires a party to kill, but I'd say with party organization can be taken down with a group of 5.

Jet, check your mail