How 'bout sinningias? There are a lot of slipper-shaped flowers in gesneriads. That second one especially looks like a smaller sinningia. I could well be wrong, but I don't know of any violet/blue kohlerias.
Many thanks everybody, for the suggestions and the link! Yes, the plants do have tubers, and I think you're right that they are sinningia types. The lighter colored one looks quite a bit like sinningia eumorpha photos I found at the Gesneriad Web link, and the purple one appears similar to several of the sinningia speciosa types shown. So at least I can label them as something more specific than "unknown gesneriad!"
