My first road bike was a Giant OCR. I loved it (well, I still have it, but it sits unridden this season because I'm testing out a new tri bike). It provided me with 4000 miles of fun and good times.
I agree with Bike Dutchess- buy what feels right. Test ride as many as possible (but not so many that it's too confusing ) and buy the one that feels like a second skin. I don't think you can go wrong with Trek, Cannondale, Giant, Specialized or any of the other big name bikes. Even the entry level bikes provide good quality and durability. Don't know about the REI bikes, or what the quality is.

Good luck- and be sure to report back what you've decided on (with pictures, to boot!).