Actually, I don't think Rainier is the best peak for a newbie, at least not a cackle of em. It's a big mountain that creates its own weather, and visibility can go to zero in a snap of a finger.
I think some of the lower elevation (lower commitment) peaks like the Sulphide Glacier route on Shuksan, the Cork Screw route on Sloan, Eldorado... are beter places to figure out how to walk with crampons, sort out clothing systems and route find. I dunno, just my $0.02