You don't need an alignment after replacing the wheel bearings. That's a crock of <img src="/forums/images/graemlins/ignore.gif" alt="" />.

If the bearings are bad, you can tell easily by jacking up the wheel and see if you have any lateral play (grab the wheel and push/pull side-to-side. You can also try lifting it vertically with a pry bar. But bad ball joints create play in that direction too. Bad bearings that are loose will have play in all orientations, with the looseness pivoting at the center of the wheel.

They can also be bad and still feel tight. But that's easy to diagnose because the rotor/wheel will have noticeable drag when you turn it. You may also feel the vehicle pull to one side while driving, due to the drag created by the bearings (my Sporty did because of a bad needle bearing - supports the half-shaft on the 4x4's front axle). Lastly, the hub may also get warm or hot due to friction - easily noticed when you feel one hub and then the other. The hotter hub may have a bearing problem.

Getting to your question on vibration, yes, a bad bearing can create vibration due to play in a bearing, much like if you had loose lug nuts (I know because it happened when I had new tires put on my wife's car - the tech forgot to torque one of the front wheels). An unbalanced wheel can do the same. If the shop didn't rebalance the wheel(s) per your request, that can still be the problem. If you have a warranty from a big-chain tire shop, then I'd recommend taking it to another shop. Hope that helps... <img src="/forums/images/graemlins/patriot.gif" alt="" />