So I picked up my bike today with freshly repaired back wheel. The owner wasn't very encouraging. "Well, I replaced the spoke. I don't know what else to do. I wouldn't change any of the components. Just ride it and let's see what happens." Well, as I mentioned I've been thinking about another bike, and I talked to the wheel expert at a 2nd bike shop where I'd been looking at bikes, and he agreed I shouldn't be having these problems, especially after getting the new custom wheel built. So, when I picked up the bike, without even riding it, I took it directly to the other shop to get their opinion. They said the components used were great, but the wheel build itself, not so much. I hadn't even ridden it yet, and they showed me how the spoke tension was uneven and the wheel was already out of true. Not so bad that I would have noticed it myself, but enough that it's probably gonna break again pretty soon as-is. So, I'm pretty sure now I ain't the problem!

So I'm paying the guy at the 2nd shop $35 to fix the wheel (basically, he's going to do exactly what CliftonGK1 mentioned above, loosen everything up and start from scratch with tensioning). Meanwhile, I've decided I'm still going to get another bike, and the Raleigh is going to be my backup. I'm going to get a Kona Dew Deluxe, which is also a hybrid but has better components. Hopefully the stock wheel will hold up for me, but if not, I have a little more faith (hopefully not misplaced) in these guys at the other shop that they can properly build a wheel. I really like the guys at the first shop, but I feel like I've been really patient with them, have spent a lot of money with them, and while I believe they have sincerely been making an effort, they just can't deliver. I guess all their other customers must be skinny enough that they don't have a problem. The guys at the 2nd shop allegedly have at least a couple of customers that they've built wheels for that are 400+ pounds so hopefully they have more experience with Clydesdales.