Before I answer--will you have a car? I assume not because you mention walking/biking--which people do, especially biking. Be sure to bring a bike lock--which I assume you'll do!
Now my answer: My honest take on West Lafayette vs. Lafayette is the following--undergrads generally live near the university (on the West L. side), and grad students generally prefer downtown Lafayette. Consider living in downtown Lafayette, but not any further out. There's still some cool places to hang out in downtown Lafayette.
One drawback of living near campus on the West Lafayette side: Noise. Undergraduates (who do tend to live very close to campus) are a tad noisy, especially near campus because there are some college bars near campus (put the two together). Also, pricing of places to live are not fun to deal with on the West side, which is also generally considered to be student/campus apartment kind of housing (not owned by the university). You'd be paying at least 1 to 2 hundred dollars more per month.
Bus-ing is reliable enough. The nearer you live to the bus center of Lafayette (near the bridge to West Lafayette), the better for you if you don't have a car. Or if you live near a bus-stop that will take you to the West side--that'd be helpful for you. The weather in Indiana can be incredibly harsh at times, so you will honestly/absolutely need to consider taking a bus sometimes (e.g. harsh winter temperatures--which Purdue tends to never cancel classes for). I will say that this is probably the biggest drawback to living in Lafayette compared to WL (dealing with weather & getting to campus), but if you can secure a place near the bus-stop of your choice, then that's great!
If you get into Purdue, you'll want to secure a spot to live in sooner rather than later--that possibly goes for any school (?). Good luck.