Since every (Catholic) church ceremony should be hosted within a church building, this already defines decisions about seating scheme and chair types. Music is expected to be on a spiritual side.
Unlimited options of decór.
The most important document is "Confirmation of freedom to marry" which is the authorization given to the spouses by higher church authority (depends of particular country). It will contain permission for marrying outside of their parish. It is signed by the diocese, valid for six months from the time they are issued. These documents must be sent within 2 months of the wedding date, so that there is enough time to make sure they are all correct and that nothing is missing.
Here are some example church wedding venues in Dubrovnik.
Old Town, September 2012
photo by Veronica
Old Town, May 2017
photo by Veronica
Old Town, June 2013
photo by Veronica
Old Town, May 2014
photo by Veronica
Mljet, Aug 2013
photo by Svadbas Photography
Old Town, June 2016
photo by Veronica
Old Town, July 2017
photo by Veronica
Lopud, June 2011
photo by Veronica
Cavtat, June 2011
photo by Siniša Štambuk
Cavtat, June 2011
photo by Siniša Štambuk