Either way it'll look great. The base doesn't have to look like eldar, it can have "we're coming to take away your world" look, you know what I mean. I think the well is a great idea looks wise, but that's just me. Sorry it broke. Your bases are always impressive btw.
Since GW has put Eldar ruins as part of all the new mini's (Harlies, Banshee's, Incubi, Eldrad) bases, I'm trying to keep the theme going.
I'm tinkering with other bits to try and make a fountain instead of a well, just need to get hold of some more clay. Really liking the airdry clay too, its not a sticky as polyclay and since you don't have to bake it, I can apply it directly to other things.
If you dab on a little Agrax Earthshade, that'll recolour the sand nicely.
That's a great idea, it should be minimal cleanup if any gets on the detailed ground.