If by "Regent" you mean Regents Seven Seas I think that you will find
that on cruises of two weeks or less they have abandoned formal
entirely. Sport coats and open collar shirts are appropriate for all
meals.

We took a Regents two week cruise - Australia to New Zealand - and it
had three formal nights which we really enjoyed. Even there, however, a
suit and tie were appropriate, tux were not required.

They were truly all inclusive. The only places your were likely to
spend money are the casino and boutiques. And there service is special.
When we checked into our room there were 2 liter bottles of Jack Daniels
bourbon and Tanquerey gin waiting for us plus a complimentary bottle of
champaign. I asked our cabin attendent if we could swap the gin and
bourbon for vodka and Wild Turkey. No fuss, no muss, thirty minutes
later it was a done deal.

While tipping is not required I did tip our cabin attendent and favorite
bar waiter the night before we disembarked in Auckland, they had earned
it.

Oh, almost all of the excursions were free. There were a couple we paid
a fee for but they were really special and well woth what we paid.