This is the way. In fact we started booking Grand Suites as we worked through from Gold to Diamond. Now that we've made it, we're going back to Jr Suites, at least for a trial.
The added cost for a Jr Suite over a balcony also comes with added perks. It's partially the perks, and partially an investment and getting more upgrades faster.
Depends on how dedicated to cruising with RCI you are. We do a couple each year generally, so well worth it for us.