Wicht
Hero
So, I think neither stats nor rule0 should really be used, no matter what edition. I don´t think these can really portrait a complex person. Stats, no matter how they have been generated, should only come up in combat.
Having said this, IMO interacting with an important NPC like the queen should be broken down into tasks, with DCs tailored to the situation. Does she respond well to flattery? Is she the trusting kind? Does she have racist views towards a certain race or nation? That´s why I mentioned the skill challenge rules as an example. When I create stats for her and come up with a, let´s say, +12 Diplomacy as an end-result, it´s global. I could go on further and add or remove situational boni.
This can get messy real quick.
Sticking with Pathfinder, which is what I play, the rules really cover this interaction already and it hinges completely on her beginning attitude and her charisma. Her level and will saves, et. al never enter into it. You determine the beginning attitude of the Queen. We'll say that she is indiffent. DC is to make her Friendly is going to be 18 (15 + cha. modifier), and helpful is a DC 23. If she has some inherent bias, I'd adjucate a -2/+2 to difficulty as appropriate. Furthermore, if the PCs are asking for simple advice its -5 DC and if they want complicated aid its +5 DC.
Again, no DM ruling nor planning is needed. You just adjucate based on the circumstances. There's really nothing messy about it.