A few questions as I haven't built a set in a while...

Good online spoke calculator with a modern rim/hub database?
Seems the DT Swiss one now restricts you to DT brand hubs whereas they used to have pretty much everything. Really, I'm not at all amused by that.

Next, I can't find much advice on running wide rims. Is there a magic ratio? Sheldon, Schwalbe, Sun, etc all have varying advice but suggest my idea is ok.

I'd like to build two 26" wheelsets with 31 and 34 mm Sun rims. They would probably have ~2.1" tires but the ability to run tires as narrow as 1.5" would be nice, if not necessary. I've decided on robust DH rims since the potholes are cracking my nice, light, DT rear rim (it was a stretch under my Clydesdale caboose).

Any help appreciated.