I STRONGLY recommend playing this game without a guide for the first time. All the dialogues are very fun and creative, there are some revelations which are better experienced naturally and there are post-credit scenes that may not make sense without seeing additional scenes. I wrote this guide to help people who have already seen everything. Not sure about the first one, but at least during the subsequent playthroughs, you are able to skip cutscenes by pressing the "S" key.

For each of the four parties I have written dialogues to pick. I have also added the dialogue to tell Mr. Davenport (after this you'll get each achievement), although if you pick the other one you will just hear some extra dialogue and be sent back to the "pick the heir" screen.

The Bellflower Hotel?
Magic act?
Assistant?
Misdirection?
Kelly?
Black market?
Weed?
Practicing medicine without a license?
Taxidermy?
Hobby?
Sleeping in a coffin?
College?
High School?
Reunions? (you will not be able to talk to her about other options after this)

What to tell Mr. Davenport:
She wants to leave Las Vegas because she has no reason to stay. I'm sure that would change if she inherited the hotel.

The Bellflower Hotel?
Professional gambler?
In Vegas by accident?
Denver?
All my jobs?
Cruise ship?
Iceberg?
Sail?
Quebec?
Hitch-hiking?
Famous people?
Cast?
Hospital?
X-rays?
Skydiving accident?
Thank the skydiver? (you will not be able to talk to her about other options after this)

What to tell Mr. Davenport:
She's suffered her whole life. You can make sure she lives comfortably for the rest of it.

The Bellflower Hotel?
Las Vegas?
Soup kitchen?
Food bank? (this step is not necessary but it makes Waterpark? visible later on otherwise there would be too many options to be displayed at once)
Assisted living facility?
Eleanor?
Summer girl?
Waterpark?
Sara's parents? (you will not be able to talk to them about other options after this)

What to tell Mr. Davenport:
She's not perfect, but no one is. She's still probably the most wholesome person who ever lived.

The Bellflower Hotel?
Wedding?
Actor?
Student film?
First met?
Third date?
Proposed?
Todd's proposal?
The ring?
High profile clients?
Gymnastics? (you will not be able to talk to them about other options after this)

What to tell Mr. Davenport:
[Lie] They are engaged. They're still getting married, just not this weekend. They also just learned that Becca is pregnant.

I hope this guide helped you. If you happen to find a quicker route, let me know in the comments and I will update this guide. Also big thanks to FMV Interactive for making this wonderful game.