I would be doing Lonesome Road immediately after Primm, but I want to get all this info about Ulysses beforehand, so I'm doing Dead Money and OWB first. I want to feel like I've scoured the wasteland for him by the time I actually meet him. I'll be waiting to do Honest Hearts much later, as kind of an "I'm tired of this adventure shit, I'm just going to take a nice quiet job as a caravan guard" thing. Obviously that won't go like it's meant to.
And Old World Blues, well, you're bound to run into it early. I don't see how anyone could pass it by unless they specifically intended to, and after getting shot in the head, a nice Sci-fi flick, some iguana bits, and a bottle of Sunset Sarsaparilla would be a nice way to relax for a couple hours.