If I were you, I'd pick a resort that specifically said *No Kids*. I spent an enjoyable week (with my kids) on Treasure Island, but I watched the couples trying to lounge by the pool and gaze longingly into their beloved's eyes... only to be interrupted by ear piercing shrieks from a 5 year old splashing his sister.
If you have kids of your own, and now have a chance for kid-free time, go somewhere where you don't have to put up with anyone else's. Or at the least, choose a bigger resort (like the Westin in Danarau) where there's space to escape.
I've heard that Likuliku Lagoon Resort is great... if you can afford it. over 4 years ago
So if you are looking for a romantic getaway in Fiji you can go in for The Fiji Orchid, Saweni Beach Road, Lautoka. I recently went for my honeymoon there. The resort is very romantic and offers good accessibility to attractions like Garden of the Sleeping Giant, Lautoka Market and others. You can also see some photos and other facilities which the hotel has on offer.
http://www.johansens.com/oceania/fiji-islands/fiji-islands/the-fiji-orchid about 4 years ago