Look at the "recipes" available and see if any of them would be useful to the type of character you play.  I like to use reloading benches to convert normal shotgun ammo into slugs.  I haven't done much with campfires except make Mentats into "Party Time Mentats" (basically Mentats with a +5 CHR boost).  And I like to create weapon repair kits with the workbench.  Also dabbling in energy weapons I find being able to convert any energy ammo type to other ammo types to be really useful.
 
The food cooking stuff I haven't found hugely useful (except when I was grinding the Desert Survivalist achievement) but raw meat usually has some kind of stat debuff that goes away after cooking.

I think this is all character based. If you only use one weapon throughout the whole game, converting ammo is really a nice addition i think. The campfire can be used easily to hunt down animals and make sutff and then sell it to get extra caps, though caps are maybe to common in this game. I dont know, i like the ideas and i've used all the crafting stations several times.

I've gotten to the point, especially using energy weapons, where I use one of the crafting benches a TON.  I mean, recycling ammo, upgrading ammo, I think it's worth it.  The food you can make is worth it too (+ stats, -FOD), but and you need to have some decent survival skills  There are some good weapons and stuff to make too from what I understand but I haven't made any yet.  Oh, and Doctor's Bags.  As a fellow HC player, you know how important those damn things are.

yeah, the crafting in the game sucks ass...i rarely used it, but i didn't find any useful weapon schematics either. Those were at least fun in Fallout 3.
it's especially bad when i remember how decent Oblivion's crafting system was with alchemy.

Once my repair was high enough I found myself converting ammo from one type to another, but there's no real supply of primer anywhere I've found. Converting energy weapon ammo has occasionally been useful. I used to carry one weapon for each ammo type, but lately I've been using .308, 5.56 and .22LR the most (the silenced varmint rifle is great for sneak crits on animals, and is dirt cheap). So I break down ammo I'm not using and build what I need. It doesn't always work well, but it does work.
 
After the tutorial of how to use the campfires, I didn't use the feature at all again. The workbench seems less useful this time around as well. Strange, when I saw the reloading bench the first time I figured I'd never use it. Now I use it regularly. I suppose if I actually took the time to learn how to use it, I'd use it more.

If you take the Hand Loader perk, you can make some special ammo unavailable anywhere else.
 
Such as .308 Jacketed Soft Tip. + 50% damage with no increase in DT on target.

Perhaps the best solution to the crafting situation would have been to make it something you could do anywhere. I regularly repair my own weapons on the run, but I never use the benches.

Its not ever pivotal and its basically telling you to pick up random shit and hope its useful later, which is not something I'm interested in doing when I already have a ton of money yet can only carry 270 pounds. They need to work on that stuff. Make the junk that you can currently use at a bench a different color so you know "hey this conductor can be used now, hey this fission battery is still just junk" and pick shit up accordingly.

I think some of the over charged energy weapon packs are pretty good.