The problem with working these issues in with price point issues is that it is a big internet out there, and it is hard to predict what prices you will get stuff at.

I read this through once, and didn't catch what you wheels are at the moment. If you aren't too heavy, and you have reasonable deep rims, you could just replace your spokes and use brass nipples and be ready to go. A proven set of reasonably good rims is a step up on a pig in a poke. But this would suppose that your rims are at least 32, and preferably 36, and I don't know who would do bladed in a 36.

If you are moving to a new touring wheel, more money is better spent on the rim. It is the weak point in the whole equation. And good rims are not terrible expensive. Also moving down a jot in Shimano hubs does not really get you worse gear for touring, can be better. LX is pretty good, or was. Butted spokes are reputedly better, but spokes are the strongest part in a well built wheel, and should never break. But many wheels are not properly built. And building good wheel is not difficult, you can build them yourself, but it probably isn't worth it. Machine built wheels, normally means straight spokes, but with the right components they will be fine, if the wheel is stress relived and final trued before you take it out. I would spend money on getting velocity rims, a good alex rim, or Mavic rim, and there are others. At the moment Velocity is the top name, at a decent price and with easy access to the rims. Get wheelsmith spokes, do not worry about them being straight if the budget requires it. Then buy a decent hub like an LX 30 bucks free delivery for the rear.

A lot of traditional English bicycles were built 36 rear, 32 front, or 40/36. There are variations as to how much load your front end takes relative to different brake systems. With standard calipers I think any of those are OK. I don't really see an advantage other than a trivial amount of weight saved in the spokes. I prefer to keep stuff as uniform as possible. At a different price point you can have wheels where all the spokes are the same length. I don't think you can do that with 36/32, but I haven't looked into it. Probably with an adjustment to flange height. But if your bike has decent front wheel with 32 drilling, you could certainly replace the spokes and nipples and never worry. Don't know what kind of bike you have, but most people seem to prefer panniers. Yes the BOB is well liked. But when speaking of the English systems they predate front racks and panniers. So another reason why we like same wheels front and back is because of the loading system.