Looking at wedding bands and wanted to know what others with similar rings have done. She wants a plain band probably 2 or 2.5 mm. Not sure on the dome or knife edge like the Tiffanys one. Here is a pic of the ring
Tiffany has many plain platinum bands besides the knife edge one, which I would not choose, either. If you have a Tiffany's in your area, I would go there and ask to try on different style and size plain bands.
If it were me, as much as I love bling bling bling, I think your oval 3 stone achieves that ( ) and I'd go for a custom fitted band that 'scallops' in and around the ovals. That's what I'd do.