We enjoyed both Renaissance Wailea and Marriott Kauai. Ren Wailea was a honeymoon trip; Kauai was a few months later.

Those were also our two favorite Hawaiian islands: probably the best two for honeymooners. We also enjoyed the Big Island: less romantic, but we went specifically for the volcano and hiking.

(Note that Ren Wailea may not be a Marriott for much longer. The Outrigger Wailea (now a Marriott) appeared to be a somewhat lower-scale property than the Renaissance, but I don't know what the rooms are like.