Too many to list but here goes. I'll just list a few.
More Pool Items especially Pool Waterfalls and Pool Slides
Relaxing in Bed and other interactions in bed including spooning,kissing,making out,cuddling and snuggling,chatting,watching tv etc.
Cars,Motorcycles,Bicycles,Boats,Jetskis and Houseboats need to happen.
More romance interactions in general including more kiss types and slowdancing. Hand holding while walking would be extremely cool.
Bridal veils and body piercings
The option in CAS to make sims as girl/boyfriend,fiancie etc.
Shower,car,sofa and tub woohoo.
A Tropical Beach Destination with Swimming in the Ocean,Beach Activities,Resorts,Sovieneer Shops and Underwater Tours via Submarines.
Scuba Diving
Fishing from boats.
Theme and Waterparks with Carnival Rides like the farris wheel,roller coasters,carousels and gondelas.