A dragon birthday game

For my wife's birthday last weekend I ran her and her friends a D&D one shot. My brief was thus: level eleven a more classic dungeon crawl dragon There were six of them. I had no clue how to balance six level eleven characters where four of these players I'd never played with before and two of the four haven't played all that much. Balancing not just in terms of encounters but time. So I winged it, basically. Which is what I think has to happen mostly anyway, in any game. Flexibility. Their regular game is more on the lighthearted, carousing, romancing end of the spectrum. My wife and her friend wanted something a bit more serious. They were here to kill a dragon and get treasure. Not seduce each other. So I proposed a red dragon hoard in a volcano lair and got to work. I knew some other fun stuff my wife would enjoy. Traps, puzzles, and Medusa. My own brief was, because people often play online, and even at the table I know these guys do a lot of theatre of the mind or basic maps in…