I just bought some real nice long sleeve knit shirts from Eddie Bauer. They are a little long for me since I'm only 5'8", but they fit real well other than that.
As for jeans, I found a nice pair at the GAP. It's the Loose Fit style. I bought them a little bigger in the wasit. They fit good, and I have a big butt. It's pretty much the only pair I wear now. I have to find some more.
Other than that, I know exactly how you guys feel. It's a problem, but I guess it's a good problem.
I have a hard time finding nice fitting t-shirts. I don't have a big neck so sometimes the neck is huge, but it's real tight around the arms and chest. Looks stupid. That's why I love the winter. I can fit real well into larger clothes and knits, yet you can still tell I lift. I'm not a guy that really likes to show off. If you're big, you can't really hide it anyhow.
I'm started to add in some cardio and fixed up my diet a little to get rid of the fat I put on during my bulk. When you naturally gain 15 lbs in 8 weeks, there's no way it's all muscle. I'm also getting ready to start training to be a 50m sprinter. We'll see where I'll be shopping in a few months.