Best prices in Vegas hands down, even better than internet prices in most cases!
Staff is very knowledgeable and courteous, they don't condescend and overcharge like other big brand retailers. I studied exercise science and a bit of nutrition in college and I know they aren't trying to blow smoke up people's skirts.
Selection is huge, they carry almost every brand I use and flavor (even the odd ones).
They also have product demos and give you samples after your purchase which is nice.