I agree with Vicarious. Personally, I wanted to look at rings with him and I told him that. I'm such a picky person and neither he nor I knew what I wanted well enough to go the whole surprise route. Plus, I wanted to try on rings; I'm female! We went at Christmastime in the DSM area and visited several places, including Joseph's on the recommendation of another ISUer. We really, really liked them. Very low pressure and great selection of what I discovered I really liked. From that, I got to pick out the setting, but my husband picked the center stone. He went back on his own at some point got the ring, and then proposed a couple months later.
So it depends on your girlfriend - is she the type to want a complete surprise (and do you feel you know her ring likes well enough or can find out from a friend - I know any of my friends or mom would have been clueless!) or do you think she might want some input?
And yes, insurance. Definitely get that under homeowner's/renter's insurance as a rider. That is really important -we found out our renter's on its own only gives a $1500 credit for ALL jewelry. By the time you add the wedding band plus your own band, you would be likely over whatever max you get. For us, the rider is $40 a year.