My thoughts alothough i have not stayed at tamarijn for a few years.
Both properties have the beach at their facility and a beach inbetwwen (druiff beach).
The resort is owned by Divi and have a great reputation.
Clean, updated, basic rooms close to or even ON the beach.
Fairlry good selection of dining places. Plenty of delicious beverages, alcoholic or no alcohol.
Activities for kids.
The pool is basic, nothing special.
The shared property is the tamarijn and everything is shareable.
Tamarijn has good food options as well, a climbing wall for the brave, non motorized watersports.
Typically from what i have seen and heard, Tamarijn has more kids.
Beach at both places is good.....................remember the ever changing geography there happens at a blink of an eye, especially in front of the Tam. (all weather realted)
Having stayed at the Tamarijn for the last five years (and having purchased a timeshare studio in the Dutch Village this year) I may be a bit biased! But I think the Tamarijn is the best overall.
The rooms may be slightly better furnished at the Divi (I haven't been in one, but you can see into some rooms) but there is nothing wrong with the rooms at the Tamarijn, and the view from the rooms is spectacular!
The staff at both hotels are lovely; our room maid greeted us with a hug last year, as did several of the waitresses in the Cunucu restaurant.
Imo, the Divi is a bit more upscale in lobby and restaurants-- Red Parrot (ala carte) and Pelcian Terrace Buffet. Their pool is larger and a bit nicer as well.
The Tamarijn is more family oriented. The Tamarijn's biggest advantage is ALL oceanfront rooms. The Divi has 4 categories of rooms, all of which, the last I checked, were more expensive than an oceanfront room at the Tamarijn.
With that said, no matter which you choose you still have the use of the facilities and amenities of both resorts.
We go for the Tam all ocean front, it is more family, but by far not over run with unbehaved kids, we are late 50's no kids. Also you can use both properties & restaurants, either one you choose you will like, again we prefer the Tam. overall for the beach, look at the 1300,1400 buildings.
If you can get an ocean view room in the "vista II" building at Divi, go for it. It's a little more quiet and the beach is rarely busy, let alone full. The area right in front of the building usually has no more than a dozen people and frequently less than half that.
We stayed at the Divi with access to the Tam. We LOVED the room we had at the Divi ( I wish I could tell you which one it was). It was on the second story and overlooked a smaller pool. It was quiet and BEAUTIFUL!!!!! when we woke up in the morning. We hardly went to the Tam just because we didn't enjoy it as much. I would stay at the Divi and venture over to the tam when you wanted. But I will say the pizza bar at the Tam is wonderful.