I'm looking for recommendations for a published (but not necessarily WotC), fun, single encounter to introduce some friends to D&D 4E. We'll be using a virtual tabletop (Roll20 specifically) for it, and are planning a relatively short session of 2 hours.
Since most of the folks are new to 4e, I'm leaning towards fun rather than challenge, and I'd like to show off the system's strengths. Particularly, I'm looking for a single encounter that showcases the tactical, synergistic combat that 4e does so well. I'd be even more pleased if said encounter had a skill challenge (structured or otherwise) built in.
I should have 7 or so at the table, so something that works well for a large party is a secondary consideration. Lastly, I'd prefer an early heroic power-level, mostly to avoid overly complicated PCs.