Both areas will give you privacy. We have been to Mismalloya 5 times and Neuvo 3 x.
Beaches are much much nicer at Neuvo Vallarta, you can walk for miles and miles, nice sand. You also see great sunsets, Mismalloya has a mountain blocking the sunset. However, Mismalloya is closer to town if you want some night life. Probably 25 minutes by bus, Neuvo V is a good half hour by cab. Mismalloya lost most of their beach a couple of years ago, it now slants down into the ocean, swimming is very rough there, beach is more gravely than sand but pool area is very very nice. There is a small village across the road that has 3 good good restaurants and they are a lot of fun to visit. I think either place will give you the privacy you would like but for long walks on the beach and romantic sunsets, Neuvo Vallarta will be better. We have stayed at Paradise Village in NVallarta, it is a beautiful resort and very quiet. We also stayed at Royal DeCameron, ( not exactly honeymoon area). large resort with lots going on. This year we are trying a smaller place Sierra. Check out Solare for a smaller quiet place, pool area looks great and everyone has good reviews of it. Scroll down thru this message board, there is a guy with pictures of the resort, they look great. Enjoy