John Grady is right. Spearfish is an absolutely wonderful, beautiful neat town. You won't find much to do there compared to Rapid I suppose, but the trade off in my opinion is worth it. In Spearfish the air seems to always smell of pine. It smells SOOOOO good. The town is extremely clean because the residents love their town and take very good care of it. If you broke down on the side of the road, you wouldn't wait long until someone stopped to offer a hand. Living is Spearfish in my opinion is going to be more expensive than Rapid. This town is HIGHLY desired to live in. So things are naturally more expensive. I suppose if you had a roommate or two, it wouldn't be a problem. There is probably more jobs to find in Rapid simply because it is a bigger town. Again, in MY opinion, Rapid is easier to handle the winters that Spearfish. It seems that Rapid is in this little "bowl" where the worst of the cold and snow seem to go around. Spearfish is higher in elevation that Rapid, so I believe there is more snow/wind/cold there. I am sure someone that lives there will chime in to correct me if I am wrong on that. I was very fortunate to live in Rapid last summer for six weeks. I worked for the cable company (Midcontinent Communications) and they had me assigned in Spearfish almost the whole time I was there. I LOVED working there and I would move back in a heartbeat if my situation would allow it!
Good luck! No matter where your at in the western side of SD, you'll love it!!