First off you would need to consider your budget.
If you love the beach, and if it were in your budget, 14 days would be perfect. ESPECIALLY after the stress of planning a wedding.
During a 14 day stay you can break up your beach days with some time touring the island, some watersports such as snorkeling or deep sea fishing and some time shopping for souvenirs.
If you do not enjoy relaxing on the beach or poolside, 7 nights would probably be plenty.
Again, a lot will have to do with your budget and what type of accommodation you had in mind.
If you have a limited budget you have to ask yourself would you rather spend 7 nights in a 4 star resort or 10 or 14 in a 3 star resort.
Aruba wedding information for a destination wedding on our favorite Caribbean island Aruba. Some other relevant Aruba tips & not so important thoughts too.