Some fonts can be used through out the invitation text and look good, while others will look good enhancing a few words only... for example the name of the honoree in the invite in one font only and then using another simpler one for the rest of the invite. So in those cases you would select 2 fonts to be used.
And don’t worry about it, because we will be sending out proofs for you to view so nothing is permanent!!! If you don’t like it pick another and we will send out new proofs. Sometimes we might send out a proof with a title “Maybe we suggest the following”.