I have found a bit of difference in tandem bike shops compared to the LBS's in my area. You can trust Mel at Tandem's East, they have a solid reputation and will really stand behind what they sell. While the margin is important to keep a shop open, they also have a ton of experience that they can share with you.
Try to test ride a few before you decide, read as much info as you can find. Start with Tandemgeeks's thetandemlink.com and also Sheldon Brown's articles on tandems.