IMHO Walmarts are disgustingly filthy ****holes, and I do my best to stay out of them as much as possible. In comparison to Walmarts, Target's are clean, have short lines, are easy to return things to, have 100x smarter people working in them, and have a much higher-end overall product line and thus clientelle.
Just to add to Matt's statement with some background info as it pertains to the cleanliness/layout/design issue (and I go on at length/ad nauseum about this in the "Wal-Mart Sucks" thread): Wal-Mart is purposely designed to be a somewhat difficult shopping experience for the average consumer.
The aisles are, by design, more narrow than what you would find at Target because if you want to get from point A (one end of aisle) to point B (other end of aisle) and there is an obstruction (morbidly obese troll in a motor cart with 4 orbiting children), instead of being able to squeeze by, you would have to divert your path to an adjacent aisle and go completely around the obstruction. It is WM's hope that, by having to do so, you will see something down the bypass aisle that catches your fancy and you will BUY MORE FROM THEM. This is also why WM has those endless aisle obstruction pallets in the middle of their main thoroughfares in the store: if you can't make a straight line to buy one thing, you might make 50 turns and buy at least one more thing than you planned on.
Target has wide aisles and I have yet to see any Target with huge aisle obstructions, man-made or no, that divert you from your intended destination. Their shelves are always clean and organized (and if they're not, the employees will make an effort to clean them up, unlike WM, whose idea seems to be "Let's build a Battle Pack fort on the edge of the shelf and see how many days it takes it to fall over in the aisle"), and the employees are, 9 times out of 10, and admittedly from my own personal experience, friendlier and less likely to look at you as if you were a serial killer for asking where the Exacto Knives are. Not to mention the fact that one of the Target employees near where I live is just drop-dead gorgeous. Ashley, thou hast stolen my heart, oh princess of the retail world.

Every time I go into Target, I am able to get in and out without thinking of committing assault on multiple shoppers and/or employees. I cannot say the same for my visits to Wal-Mart. While I hate hate hate Target's exclusive, well, exclusivity these days with Hasbro and their seeming inability to handle these exclusives in a reasonable, "everybody gets one" manner, I'd rather shop there than walk into Wal-Mart and run the risk of catching lice.