Have knotty pine also (pack with plenty of insulation (husband just put nails in half way to timber rafters to hold insulation and them put on T&G), five years up, know two others houses with it also, one has what "fake" beams at the angles which look lovely. one has recessed lights which also look brillant, have ceiling light with fan myself.
Have seen T&G one painted the popular sage green - looked very smart and also my doctors surgery just has the ceiling plastered which i feel is a bit boring (was originally a private house).