Fairmont Hot Springs is 15 miles west of Butte on interstate 90. It has a hot pool, swimming pools and a three-story water slide. It also has golf and tennis. You can rent a room, hook up an RV, or just stay for the day.
It happens at midnight when St. Patrick's day begins. The police block off the streets, the crowds gather by the hundreds and the local chosen few get to paint the shamrock in the street of a busy intersection. Maybe you had to be there but it was very fun.
If you don't mind the scenic drive, then around 30 miles east of Butte. Right next to the town of Whitehall, there is a new outdoor theatre, it started two summers ago, and has been a great family event. It produces Lewis and Clark's "Journey of Discovery." Which is historically accurate, and great fun! This year the theatre is planning some new shows along with the Lewis and Clark show. On in particular is an epic western adventure. It was written right in Butte, by an 17 year old. But no plans have been made yet on this or other shows. Details will be released soon and I'll keep you posted on this tip. When you get to the website click on the Jefferson Valley Presents link.
Great little public park called Lost Creek, just west of Anaconda. Waterfalls and meadows with creeks that are jack-full of trout, old gold mining camps, and postcard scenery.