This week I made the Jungle Hollow (35x35), a map that looks like it probably has nice acoustics. Maybe you can play with that somehow, but don't ask me how. Anyway, you can bet all kinds of critters from the jungle would gather here for water as well as your party, so if you've got a big bad monster that you want your party to catch a glimpse of then this might be a good place to do it! Introducing a gigantic dinosaur and the signs that it's close would be a cool way to set yourself up for tense moments later, I think.
Btw, I'm going on a trip this weekend so next week's map will be a bit delayed- sorry about that! I'll put something together as quickly as possible with the time I have, but I bet you could expect it next weekend. But who knows, maybe I'll be competent and make a map quickly for once?