Hi Quailhiker and welcome to Chat!
I'll just share briefly our experience 2 weeks ago with Johnson's campground. We came out of the backcountry 1 night early midweek, so we didn't have reservations anywhere in St. Mary. Johnson's still had availability at 2 pm (as did KOA) but they were down to their last 2 sites. We liked that the sites were in wooded areas, as compared to the KOA sites where it seemed a sea of RVs and campers. We also felt the $27 or so was a good deal. This included 4 tokens for the showers, 6 minutes each. It varied quite a lot on how close together the tent sites were; some did lack privacy, whereas some had nice quiet hideaways in the trees. We lucked out in getting the picnic area at the end of the RV's. This placed us off by ourselves against the wood's edge....NICE!
And the area was atleast twice as large as the other available tent site.
We used the showers up by the front office (there is a 2nd shower complex toward the middle of the campground). Two were functional and we only had to wait on one person ahead. It was quite clean with abit of cubby space and hooks. I recommend purchasing an extra token for $4 to have plenty of time.
You mentioned using this campground on the front end of your trip but should you need laundry facilities later, they have 4-5 washers/dryers each and we were out of there in short order.
Best of all, their restaurant is a mere stroll to some homemade bread and fine soup. To our disappointment they were out of Mile High Huckleberry Pie for the evening but it has been a favorite in the past. Breakfast there is quick, plentiful and with a good cup o'joe! Service at both the restaurant and front office was friendly.
There is an extensive review of Johnson's on a previous thread that you'll find helpful. We had a very positive first experience with them.
Hope you have a terrific trip!
Tam
One last comment: We did see a black bear 40 yards from our campsite and reported this to the front office. The office manager told us that one had been apprehended recently near St. Mary Lodge for going through dumpsters. Walking out the door of their office, we immediately saw their dumpster lids lifted up open by garbage overflowing. This was still the case several days later when we returned.