Seconded on "ride the hell out of whatever they have in the shop". Your budget is rather generous, you should be able to find a decent bike, but don't forget to figure in the cost of a lock + air pump + helmet + other necessities.

And another bit of advice - if you do go to the bike shop, don't tell them your budget's that high. Bike shop salesmen, like any other salesmen, will find a way to take it from you.