Just hatched a bunch of 5k eggs at the same time, getting an Ekans, Nidoran-F, Slowpoke, Mankey (which was somehow new to my Pokedex), and a 770 CP Growlithe, which was my best of the bunch. Haven't had a 10k egg since the first week of the game, so hopefully now that I've cleared out a bunch of spots, I can come across a few of them.