Syrris:
I suspect that Essentials-only would put off a lot of players given that martial classes get stuck with relatively limited options (part of the attempt to retro-ize 4E) and many of the interesting themes introduced in 4E were entirely absent (for the same reason).
Yes, some people don't care for Essentials, though - for all its lack of options - at least some of the martial classes are still fairly enjoyable. The thief in particular gets praise. And a group could get by without a single martial character, if none of those classes enticed anyone. There's a divine defender, an arcane striker, and an arcane controller, just in the first two books.
I tend not to use themes anyway.
All that said, I'll definitely consider what options to go with.
Syrris:
The Slaying Stone is also easily extensible to include belowground dungeon crawl elements if you want to include some of that per the other thread. While it's unlikely that you'd find a gigantic catacomb, it's reasonable to suppose that there might be smaller sites dotted about the town and immediate surroundings (some of which might predate the place).
True. I finished reading through it, and the impression I get is that it's very much designed for a group to take it where they want. In fact, the titular quest doesn't seem like it's really even intended to be the focus, just a jumping off point for exploration.