A mod to do this... Add to fishing the ability to chat.. Maybe interactions like kids asking for help with the bait. You can think of others like it as well.
Herbalism could use a makeover.. First thing that bugged me was that even after you identify a plant, you can't tell what the plants are by pointing at them. Next it would be nice if your sim could help the Hermit with his/her garden, and have it raise friendship and social. Found another. When you harvest the wild plants you gain skill for gardening but none for herbalism. Leveling herbalism would go much faster if you gained skill for harvesting wild plants. You can have your sim view the wild plant, but it does nothing toward identifying the plant. If there isn't some in the game, gloves to keep the sims hands safe from poison and others if any. Would be cool if you could sell your potions to the guests when your on vacation.. I know they would all buy the insect repellent and maybe the anti sad one. See if possible to make it so you can put food you cook on grills or stoves in portable cooler.
Adding Animation to the Horse Shoe game with skill gain and a better chance of getting a ringer with each level. Horse Shoes has a bug where your sim plays the game wail eating, also they will get called away to play all the time. This bug has not been a problem at home need to test it more, just at the camp site. Same with Foosball on the adding skill gain exc. There may be others I'm not thinking of.
Here is one more.. Adding to the Programing Create Game on computer.. You have a few choices for type of game like 1st person shooter, D&D, or Dungeon like the classic games, Eye of the Beholder, Heretic, Wolfenstein 3D.. Another type like WOW and Diablo. Your sim should become a millionaire making games.