I thought the Jet sidequest was pretty fun. Myron is a bit of a dick, though he's got really high science and technical skills, so if you've completely skipped those yourself he's a pretty good tech monkey. He's worthless in a fight though, so not a super big deal to skip - mostly useful for combat heavy characters who feel like skipping Science completely but still want to do sciency-quests.
However, if you have really poor science skill, you NEED science skill to get the best companion. And Myron's brain is pretty valuable if you [information redacted for spoiler reasons].
I think you've missed Ghost Farm, San Francisco, Navarro, NCR, Broken Hills (I think you hit Redding already, right? I forget.) and [censored], of course. I'd assume you haven't heard of most of the ones you've missed, except for the Ghost Farm which you probably just ignored (not a big deal). The names don't mean a whole lot, so I don't mind saying them. I'd assume your character hasn't heard of most of them yet. I'm skipping the more "surprise-ful" locations there.
Fallout 2 is a pretty big game.
The cave you rescue the trapper in has some other stuff that's worthwhile (I forget exactly what), but don't know if you really need it at this point in the game. Make sure to bring a good pair of boots unless you like extra toes, if you do go back to finish it at some point!
Number of companions is based on Charisma - how much are you at now? You can always pump some charisma drugs or dig up a pair of shades in Golgotha for the CHA boost if you need it to grab another companion.
Anyways, I vote for NCR next. Broken Hills is really fun, but it always brings me memories of being surrounded by Goons and forced to tell jokes and make them left in order to avoid being murdered and having my stuff added to the "loot for those who make us laugh" pile. (I spent way too long playing the Fallout MMO, and the Something Awful folks used Broken Hills as their base of operations.
)