BigLug, I see no one has answered this yet, so I'm going to jump in with a for-what-it's-worth response. How tall will be the sides on your raised beds? Lots of times, once you've loosened the soil and added plenty of compost, you don't need to add any soil.
On my own beds, I occasionally add a bag of Ace Hardware top soil. I don't do it all at once, though, and I mix it in good. Plants recognize different soil levels, according to my Shepherd Ogden book (I think it was his book), and their roots might stop once they hit a new level.
If you buy bagged top soil, buy one bag of, say, three different kinds to see which one you like the best. If you are having your topsoil trucked in, check it before you buy it so you know what you are getting. One of my neighbors bought what he swears was a load of sand last year. I suspect he is wrong. He's a North Dakotan, and they can afford to have higher standards than Wyomingites when it comes to soil