There are a ton of things to unlock in Playboy: The Mansion, based on your various actions. This is the complete list of what to get and how to get it in Mission Mode. The requirements are different for Freeform Mode, but all items are still attainable no matter which mode you are playing.
Clubhouse - Unlocked after completing Mission 5
Grotto - Unlocked after inviting the agent to the special party in Mission 4
Pool - Unlocked after completing Mission 1
Better photoshoots
If you take a picture of a girl while she is winking (so that the picture has one eye closed), it will boost your photoshoot. Variety is the key to a great photoshoot. Get pics both on and off the bet, couch, or prop. Get some clothed and some topless. Get objects in as many pictures as possible. Get as many winks and raised eyebrows as possible. Also, fit them in the picture both close and far off.
Increase Charm
To increase the Charm of people, have them follow you to a mirror and tell them to "Use". Repeat this several times.
Increase Intelligence
Get your journalist to follow you. Take them up to a bookshelf and tell them to "Use". Repeat this many times. Eventually you will have increase their Intelligence. This also works with everyone in the game. Just like how you can raise your photographers and writers intellect by making them follow you and telling them to use bookshelves, you can also do for Hef. His intelligence will also rise, but it sometimes will not work for the different bookshelves.
Increase Physique
Have your Playmate follow you to a piece of sports equipment. Tell them to "Use". Repeat this several times. Eventually they will have a high Physique. This also works on everyone in the game.
Making Parties Last
By removing all your doors to an enclosed area celebrities will have no choice but to listen to what ever you have to say. This means an easier way to get interviews, photo shoots, essays, ect. Just because they're tired doesn't mean they won't do these things. Make sure you have enough money to get new doors installed if you what the party to end.
Publishing
When you have a playmate do a centerfold. After you publish them, they can do an essay, cover shoot, or an interview. It is good to be their friend before publishing your magazine.
Roster Character Editor
Allows you to edit the name and appearance of all fictional staff members and celebrities. Note that ratings, specialties, and occupations cannot be edited. You also cannot edit anything about storyline people in Mission Mode, such as Scotty Powers or Ki Kji. Unlocked after completing Mission 2.
Unlockable Items
Brass Bed - Upper floor only. Unlocked after completing Mission 9
Bunny Back - Main or upper floor. Unlocked after completing Mission 3
Butt r fly - Main floor only. Unlocked after holding the fundraiser for Operation Validation during Mission 5
Leg-O-Lamp - Main or upper floor. Unlocked after doing an intimate action with a girl during Mission 3
Massage Table - Upper floor only. Unlocked after publishing an issue during Mission 2
Michelangelo - Main floor only. Unlocked after publishing the Playboy Philosophy during Mission 4
Obsession - Upper floor only. Unlocked after finding Ken Willard during Mission 5
Olivia's Hef - Main floor only. Unlocked after completing Mission 4
Regency Chair - Main or upper floor. Unlocked after completing Mission 8
Regency End Table - Main or upper floor. Unlocked after completing Mission 6
Regency Rug - Main floor only. Unlocked after completing Mission 11
Regency Sofa - Main or upper floor. Unlocked after completing Mission 10
Trampoline - Pool only. Unlocked after getting two girlfriends during Mission 3
Ultra Extreme Dance - Clubhouse only. Unlocked after publishing Karmyn Chase on the cover during Mission 5
Unlockable Outfits
Artsy Bunny Shirt - Unlocked after cover shooting Karmyn Chase during Mission 5
Barely There Plus - Unlocked after signing Carmen Electra to a contract during Mission 8
Leopard Flares - Unlocked after holding the sexy Grotto party for your Playmates during Mission 7
Plaid Skirt - Unlocked after holding the special parties for your staff, Playmates, and girlfriends during Mission 7
Playboy Mini - Unlocked after getting a high romantic relationship between Markus Jacobski and any female during Mission 6
Retro Zip-Front - Unlocked after forcing the two enemy staff members to make up during Mission 4
Shoulder Wrap - Unlocked after getting a high romantic relationship between Karmyn Chase and Builder Paris during Mission 6
Stars and Stripes - Unlocked after inducing love between Wendy Bigmoney and Ciro Burrow during Mission 8
White Peek-a-Boo - Unlocked after getting Penny Starks or Sandra Bellore as your girlfriend during Mission 8
