My 5'2" sister in law is looking for a road bike to compliment her running. Any bike nuts out there know what is good for under $2K, I have been telling her that getting the best wheels is the most important but I could be wrong. I'd rather it be second hand or old model to get good stuff cheap.

She is not competing but if she gets into it, she might in the future. (She has done 3 marathons and 2 trailwalkers.)

i believe giant make a womens specific model that is good value - cant remember the model though
i bought my wife a SUB (which is made by avanti) - it's a nice entry level road bike, they have a range at different price points. check out http://www.sarahulmerbrand.com/bikes/road-sport/subzero-1/

Equivalent of the mens Defy 2, it's called the 'Avail'. Although I own a Defy 2 and my wife an Avail, I don't believe they represent particularly good value for money. If I had my time over again I'd buy the Cell 'Team' bike. Quality build with 105 running and brake gear for about the same money as the Sora in the Defy / Avail. In a women's specific bike (which really is just 165mm cranks, different seat, shorter reach bars and occassionally a shorter top tube / seat tube ratio) I'd look at the Sub range.

If It's a first bike and the 'bling' of newness is not necessary then there is generally some quality gear available second hand with low km's on eBay (and other places like the LBS). Pushbikes depreciate faster than cars and so you can find yourself with a carbon frame ultegra fit 2006 type bike with maybe 3000km for under $2k. That's a bargain if it's in good nick.

saw the giant avial alliance. Its got an old drive train but for a bit over 2k to have a carbon frame looks good. I got shimano R550's for $200 of ebay, that must have been a bargain, anything under 3k only has R500's

The Sarah Ulmer bikes are pretty decent but not necessarily good value. They also usually have an exact equivalent in the unisex Avanti range. It might not be necessary for her to buy a ladies specific bike. A small sized unisex bike would probably do just fine. If she feels she needs it she can always adjust and even replace the stem and controls can be adjusted for smaller span hands. Things like womens specific seats and narrower bars are available too if necessary.
For the money she wants to spend she should be able to get a bike with 105 gruppo, carbon forks and seatpost and seat stays with no problems at all. If she wants to get a used bike or a clearance bike brand new a full carbon (although not great quality) would even be possible.
Remeber that gear will easily run to $500 though so she obviously needs to factor that into her budget too.