Seattleite here, being a tourist. Caverns came recommended by a Billings' friend. Definitely worth the drive from Bozeman. Check their schedule online.

Though I read the web description/warnings, I was woefully ill-prepated for this Classic tour jaunt. I'm fat, forty and female and I went alone since here on business. I was last in line all day but Lily never made me feel badly or a burden. Kind, courteous...I felt safe all day. The jokes/puns/facts were perfect. Would recommend for anyone not already on the verge of a heart attack or claustrophobic.