Wedding rings are a standard outward showing of the commitment that two people make to each other. I don’t think that the partnership rings should be too large.
Men’s rings should be understated and muted in color, not a lot of "bling". Women’s right can be more ornate but try to remember that this is something that you are going to be wearing everyday for many many years.
Don’t go for rings that might get you robbed which happened to friends of mine in Spain! Too big and too shiny could result in an unexpected mugging.
One more thing, please don’t go for the tattoo rings. I can’t think of any that could end a marriage faster than a tattooed wedding band!! Tacky!