First of all, I have to say that the renders and the characters are looking good. I also like vacation as a setting because it allows for a set period of game time and a plausible setting for passing time.
Characters
When people go onto a holiday they tend to bring a lot of clothing. Day-time clothes in a warm climate would tend to be more loose and ordinary while for night time activities the characters could put on something with more bling and show more cleavage (but not too much) especially when attending dinner or going to a night club.
As for the number of characters, I would much rather have a story, build up, interactions and content for a just a couple of characters than shallow content for many characters. Some supporting characters can help sell the main story better and make endings feels more "real" e.g. in this game one such character could be the father figure or a rival who can cause an early game over scene such as: After failing to woo Karen, the game skips to the end of the vacation and screen follow with text: "Family <surname> had a wonderful vacation. Karen found the spark with <father> once more. Blair had a summer romance. And Daniel... well he had fun too" with Daniel all grumpy and kicking rocks. A father-figure rival actually would not need to be physically in the game but could be present in the character's discussions. For example, perhaps Karen confides in Daniel and talk about her marriage.
Build up and mini-games
I find that build up is one of the hardest things to get right in these kinds of games. Usually devs just jump to the spicy content after some lukewarm dialogue. I would like to see the level of intimacy between the characters increase slowly. For this, mini games like the dancing mini-game is a great idea! Other activities like that where the character can slowly but surely explore new territory will help sell the progression better.
Which brings us to the important point that development of the relationship between Daniel and Karen should not be a linear grind. For example, suppose there is a domination path for Daniel where he tries to swoo Karen. So Daniel will try to make advances but Karen should realize that what is happening is inappropriate and wrong, and set him straight in a very strict manner. For example, too eager touching would be met with annoyance and scolding, and a first attempt at a kiss on the dance floor will cause her to pull back in "what in the earth are you doing?" manner. It should be up to the player to get past these obstacles, and even if you did everything right, the story should be done so that there are always some ups and downs.
Game and scene endings
Speaking of endings. I would much appreciate more contentful endings with more control on how content ends. Regarding the game endings, ideally there would be both bad endings (like the one above) and good endings. And the endings could be more than just summarizations of how you did during the game. As an example, the ending of the Housewife game could have been a playable epilogue from the kids perspective. The family would be back home again, the playable character is the kid, it would be night time and he is in his bed, credits and scores roll on the side of the screen but the player can choose to click on the bed to go to sleep OR (if you did well enough) click on the door and wonder into the mom's bedroom and "drive" home the victory.
With scene endings I would like to be able to choose where to finish (face, mouth, tits, ass, etc.) especially so if the route the character is on is the domination route.
Phew, sorry for the long write. :) Super excited to see Sunkissed when it is out - it is looking great!