wedding invitation wording using name suffix – Jr., Sr, III

I was wondering the proper wording for names with suffixes; my father is a Junior (John Doe, Jr.), and my fiance is the third (Bob Smith, III).
Should I spell out Mr John Doe, Junior;
Mr Bob Smith, the third
or is abbreviating the suffix appropriate? The problem with my fiance’s name is the III looks more like “J’s” in some of the more flowing fonts that we like.
Thanks for any help!

Rebecca Black, Etiquette By Rebecca

Dear Lots of Titles,

If you have room on your invitation, you may write out: junior. It would be in lower case. If not, Jr. would be fine.

If you choose to use your groom’s suffix, III would be best. You could use the 3rd. But, it isn’t as well received as III.

Best wishes,