Here's my breakdown. Since I rarely buy ANYTHING unless I try it out or use it first, this is what I do:
-DVDs for shows or anything disc media- Online. The music I usually buy is from iTunes . Once in a while I buy them at a store, but why bother when most of it is crap and it has nothing that I'm looking for?
I tend to go for used and or discounted.
-Books. Amazon, Target, CVS and Barnes and Noble, either online or at store. Well prior to borders' collapse, I went there with my sis and I stayed either in the Comics, Manga or Magazine section, and I loved the History section at the one in Ann Arbor and the one in Chicago. I love the feel of a bookstore because I never had a good library until High School aka I had a very small one so it was not only a library of sorts, but I could preview the things I wanted to read prior to buying it. Nowadays it's online because I know what I want to look for , but it is not as frequent as I used to do at Borders. Case in short: while I love ebooks, holding a real one is far less distracting than on my tablet, though it has gone away mostly.
Since I love used books ( if a semi decent quality) , I'll go for those online because if I can buy a book series for really cheap, I'll do it that route. I use coupons to buy mags for that once in while approach.
-Clothes or other Apparel: Stores Period. I won't and never will buy clothes online because frankly, I ain't gonna waste my hard earned cash on shipping it back and I'd rather be able to change in it and get a feel of said clothing. Shoes? Well, that's a different story as you can wear them once and it won't be soiled by your sweat and anything else,though I prefer offline as well.
-Imported stuff: Online easy.
-Food (nonperishable/perishable ): Offline unless its rare foods or something of the sort, but I have never bought anything tangible like that off the internet. I would, but unless there's free shipping, screw it.
-Electronics: Online after I preview them in stores. At Apple and many dealers, always check the refurbs if any and for my picks , I just went into the store, looked at it and smiled. Would I trust to buy a Macbook Pro or x Apple device of that nature online? Not only would I be very uneasy on such prospects shelling out that much money, but for anything , the atmosphere of the store itself is enough for me to buy it there. I'd do it online, but its hard to say really.
It all depends on availability of said item whether its online or not , but at places like Best Buy I really love the fact that I can call over the phone and have it reserved or online.