On second thought, there seems to be a pattern for these irregularities:
przyjaciel - przyjaciele - przyjaciółmi (not przyjacielami)
ludzie - ludźmi (not ludziami)
koń - konie - końmi (not koniami)
dłoń - dłonie - dłońmi (not dłoniami)
but then, you've got: słoń - słonie - słoniami (not słońmi!)
...so I give up. It's worse than sudoku, especially after all that beer which I bought for the Poland-England game.
Hope you have good memory, nothing else can save you :)
good examples, and again, there are palatalized sounds here, so they're probably the culprits.
As posted prior, the transition from palatalized to non-palatalized (or vice-versa!) depending on the case, still causes some confusion for me:-)
