Welcome kjane82!
Congrats on the new home! Lucky you to have such a great feature in your DR.
Well, there are several ways to accent your ceiling. Since I have no idea what type, color and style your DR furniture is and wall color, I will just have to give you several links of photos, accenting octagon ceilings. More info would be great!
Installing decorative crown molding is one way and paint is another. Using a ceiling medallion around you chandelier and crown molding is always nice. Another way is to hire a artist to paint a mural on that part of the ceiling that you like. Not sure how much you want to spend doing this.
Here ya go! Look through all these links and see what appeals to you:
http://www.ehow.com/how_4923020_decorate-room-octagon-ceiling.html
Artwork: http://www.talariaenterprises.com/images2/5239a.jpg
Scroll down on this one to see some interesting ceilings:
http://homedesign.marthastewart.com/category/paint
http://www.fotosearch.com/bthumb/CSP/CSP028/k0280358.jpg
http://www.studiofourtwofive.com/ceilingmural.htm
http://www.samzwemmerpaintwork.co.uk/int_mural-egyptc.htm
Paint: http://www.bhammls.net/BAARReports/media/433885_0442500.jpg
Decorative tin tile is another way: https://www.americantinceilings.com/estore/media/large/3-ssg-300.jpg
Plaster: http://www.coulhousehotel.com/on-the-inside.asp
Wood molding: http://www.mcintoshestatehomes.com/REALTORS/1600_Tokalaun_Court_Lucas_Texas_interior_files/DSC_0517.jpg
I have even seen mirrors installed on ceilings. Guess this is good for avery modern DR to make it look bigger:
http://www.accurateglassandmirror.com/nss-folder/mirrorsgallery/Octagonal%20Ceiling%20mirror%20with%20matching%20mirror%20dining%20room%20table.jpg
Scroll down on this one too:
http://homebuilding.thefuntimesguide.com/2007/02/coffered_ceiling_picture_idea.php
More here: http://primed4design.blogspot.com/2009/03/march-decorator-of-month-naturally.html
Just depends on what appeals to you to fit the style of YOUR DR.
Do you have wood flooring or carpet? If wood, I would get a large octagon area rug for under your table with colors in it to match your DR or wall color and to accent the ceiling more. Make sure it's big enough so when you pull your chairs out they are still on the area rug.
http://www.homedepot.com/Decor-Area-Rugs-Mats/Nourison/h_d1/N-5yc1vZ1xr5Zba6yZ12h/R-100040406/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053
Well, now you have lots and lots of food for thought. Let us know what you think and it would be so great if you girls would fill out your profiles so we can get to know you better. ;o)
Of course we LOVE to see picture here, if you can share some.