We have some thoughts on building a place that is mostly static (basically one simple server script) with all parts anchored.
Is it viable to have 100 players in the same area on a server (thinking of the network traffic, mobile devices etc)? Or can the 100 player limit only be practically applied to multi-place games?
Well, from what you are saying you should be fine, but you would have to do some testing.
The problem is that testing this would require that we get 100 concurrent players to test with. But on the other hand I guess we could temporarily try to crank up the server size if we get some traction with the idea. 
I hoped that someone had done it before me and could share some results.
Yeah, I think you should try it and then just see if you ever run into problems. If you do, then turn the size down 