We did a one-shot where we were all halflings and gnomes (technically two races, but not really....) investigating a cave of Kuo-Toa. It was a blast, and not just because we had NO idea we were fighting Kuo-Toa.
My Halfling Druid was awesome. The gnomish bard (With a whip!) showed the group that bards don't HAVE to suck. We had a halfling sorcerer who was amazing. And then there was the poor gnomish hexblade...
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I've always wanted to be in an all-dwarf group. I've got a dwarven ranger/rogue that I've wanted to play for years. Maybe one of these days.
In 2e, we did the "all-elf" group, but it wasn't out of Player choice. The GM actually said "okay, it's an elf-only campaign", so we all had to make elves. And, for some reason, in 2e we were pretty anti-multiclassing. I can't remember what I wound up playing; probably an elven ranger or rogue. The game didn't last very long.