Boots for Mt. Rainier (...and beyond)

I'm planning to climb Rainier this coming summer and want to get some mountaineering boots that are suitable, with enough time to really break them in prior to the climb. I have some experience at altitude and with alpine/glacial travel but I have always been using rental boots when needing crampons.  I plan to use Rainier as a stepping stone to some other big mountain climbs and want boots that will both work well on Rainier as well as having versatility for even more ambitious climbs thereafter... Its a big purchase so I would appreciate any recommendations? thx