You've probably done it but Lucky Old Sun is fun for half an hour.
Exploring vaults 3,11, 21, 34. Each of them have their own quest. You get the vault 21 quest off a guy in camp mcCarran, vault 34 from a pump station east of vegas.
A guy in mcCarran gives you a bounty for some fiend leaders, pretty fun.
If you haven't done it the Boomers have a few quests.
Jobs for the crimson caravan.
Jobs for SIlver Rush.