Leebo

Any kind of outdoor store like REI would be a great start. Um, slim fit? Not for me either. I did pick up some ( wait for it) XXL slim fit Patagonia woo stuff. Fits me great for I need the longer sleeves and body.

mtn.cyclist

I buy vented button front shorts from Ebay. Columbia and Patagonia have polyester shirts that are wicking, vented, and wrinkle proof. There are tons of fairly inexpensive shirts to choose from.

badger_biker 

This thread caught my eye since like the OP I will be doing some touring in Europe in a few weeks and was looking for something to double for riding and street wear use. These ATD products looked good and after a couple of emails with their very helpful customer service I ordered a large shirt and small shorts. The front and rear zip pockets on the shirt seemed like a handy feature for passport etc. I'm 5' 10" with a 32-33" waist and the sizes I ordered are the complete reverse for my usual cycling clothes so their sizing seems a bit odd. I'll post a follow up on their fit after I get them.

I have an older REI Sahara Tech shirt and can recommend it for biking with sleeves rolled up but they are a bit short when down and reaching out to the brake hoods. Perhaps a tall size is a better option or maybe the newer versions are cut different.