Contemporary pendant lights come in all different shapes and sizes (including cubes, teardrops, tubes and so on), so it really depends on which ones strike your fancy. Diameter is something to consider because you don't want to overwhelm the counter seating area to come, and that's something that will really vary depending on what kind of lights you like, but so is hanging height! Here's some general advice on pendants.

Ceiling pendants should hang 12-20” below an 8’ ceiling. Add 3” for every additional foot of ceiling. There needs to be at least 1’ of clearance for people walking below the pendant. For hanging pendants above an island or table, start with 28-34” above said table as a rough guideline, but make sure to consider the sight lines of the people in the room so no one gets glare in their eyes or runs the risk of hitting their head on the pendant. Mount a pendant every 2 feet or so above a kitchen island.

Take a look around http://www.lightsonline.com/mini-pendants/ (you can choose to just look at contemporary or transitional over at the left!) to give you an idea of what you might like to hang and then start making a note of diameters and so on--you're sure to find your favorite new lights!

Thank you Lights Online. I'd still love to hear from anyone with direction on diameter size! Part of the problem is that there are literally thousands of pendants to filter through on lighting store websites. Very overwhelming!

I would look at the 4" to 5" diameter range if you are hanging 2 pendants in a span of 59". Anything larger might overwhelm the space and anything smaller will look sparse without a third pendant.

I would agree with LBC Lighting - I would definitely stay on the small side. How about using a clear glass fixture - that would give you the contemporary/transitional look and take up very little visual space. I would do a simple cylinder or similar shape.

Thank you Thank you Thank you!

How about this one?
http://www.lampsplus.com/products/feiss-urban-renewal-5-and-three-quarter-inch-wide-bronze-mini-pendant__2g293.html

You can do pretty easy searches through LIghting Universe or LampsPlus.

Thanks, Kathryn I like that. I think I'd like either a cylinder or one with a rounded shape though. I'm in love with the Jonathan Adler Capri pendant in blue. Is it too big?
http://www.lumens.com/capri-1-pendant-by-jonathan-adler-uu235043.html

What about two small chandeliers???

I like that, too, rhsmith, but it is quite large. I would mock it up out of cardboard or paper and try it out. Even more than the diameter, I think the 18"height might be problematic.

Could you use the Jonathan Adler fixture over a small table?

That's a good idea. Who knew finding the right pendants would be so hard? I really appreciate your advice.

Kathryn- thanks again for your advice! You helped get me on track. I found a great pair if pendants at Ferguson yesterday. I was hoping to just find one I could live with (I think most are really ugly) and instead found one I love. I went we'll over my original budget but I think it will be worth it. See the Mini Mason by LBL lighting below.

http://m.lbllighting.com/Products/Fixtures/Low-Voltage-Pendants/Mini-Mason-Pendant

Oh, VERY cool - I really like that one! I think it's worth a bit of budge-busting ;-) You're very welcome. Post photos as you go along - can't wait to see how it turns out.