I've done extensive documentation on setting up Cases, but this is my first foray into setting up Cases directly in Lightning, so I will document any gotchas or special things I find. I think the main thing is going to be the difference with Case Feeds. 

Documentation. 

Console

This setup I'm doing does not use Console, so I will update this page later when I use Console on my next project. 

Lightning Page

Like all standard Lightning pages, the page layout is horrendous unless you have no details on your Case record, and EVERYTHING is done via the Activities. 

I would do

• Details on the first tab
• Files and attachments on the second tab
• History on the third tab (and maybe related Cases)
• Chatter on the right hand column in the first tab
• Activity in the second tab

As there are not many buttons, I would set buttons to 1 (or 2 if you add a Close Case action). 

Page Layout

Don't use the Feed Layout, it's superfluous for Lightning. The Compact Layout now controls the Case Hovers. 

Remember to

• Create and assign your Compact Layout 
• Override Global Layout for Lightning buttons
• Arrange the buttons 
• Take Solutions and Case Comments off the page layouts
• Take Attachments off (unless you are using some form of automated tool that can only add Attachments). 
• Add Notes

Edit the properties - I would turn all these off unless you have a very defined case process where the case changes owner often

Case Feed

Well the Case Feed is not really the Case Feed anymore, it's just Chatter. 

Jen Lee has a good blog post on creating a Flow for Case Comments if you can't use Chatter, but you can now do it with a Quick Action. But otherwise take Case Comments off your page. 

• Create a new Follow Up Quick Action setting the subject, and the date to be in 2 days time, and the assigned to to be the user. 
• If you really want to re-create the Case Feed, create the Change Status, Change Owner, and Close Case (see below) Actions. 

Email

Adding the standard Email Action to the Case Page Layout does nothing. Oh, you have to have Email-to-Case turned on to be able to email FROM a Case. Bizarre! (I suppose I've never set it up any other way before, and in this org, they are keeping it really simple and will not use Email-to-Case). 

See the Documentation

OMG WHY oh why is the Case Email Rich Text editor DIFFERENT than Lightning Emails? Why? This is so bizarre! You can actually insert Images! Amazing!!!! 

Case Emails

Lightning Emails

And Case Emails is the EXACT place you don't want people using garish font colours! 

Ok there is a lot to know about Emails in Cases, similar to Emails in Cases in Classic, and I'm not doing a complex setup here, so I will skip this bit for now. I will need to delve more into Email Templates and settling the correct From Address as an Org Wide Email address and setting a template based on the contents of the case (or using Quick Text and Macros). 

I'm also not doing Knowledge this time around so adding articles to Case emails is not covered yet (if it in fact actually works yet). 

Quick Text

Quick Text works really nicely in Case Emails, so unless you have fancy requirements for emails, I would use Quick Text. Remember it's ctrl period (when it's typed ctrl+. is reads as ctrl then the plus button but that just increases the screen size in the browser). 

Close Case

The Close Case button does not show on the Case. There is no such thing as a Closed Case Layout anymore. You have to create all that yourself. 

Options are:

• Add Path to the Case (ugly!)
• Just set the status to Closed (no Close Reason)
• Create an Update Quick Action to set the status to Closed with the closed fields
  
  • Add a Related Record component to the page with the Case Closed Quick action to only show conditionally when the case is Closed. 
• Note that Close Case Action will never appear in the top right hand corner - it will always appear in the "feed"

Create Case

• Create a Quick Action from the Account and Contact to create a Case. Prefill everything you can. 
• Add the button to your Page Layouts.
• Make sure you change the Lightning Page Layout to ensure the New Case button is visible, and add the Related List of Cases to a prominent position. And remember to set up the Fields and field order on the Related List.
• Remove Create Case from the Global Actions menu
• Remove the New button from Cases List View

Mass Quick Actions

• Cases is one of the objects you can Change Owner via a Mass Quick Action - so set that up. The standard button on the Case List View don't work.  
• You can't make the Owner field required on the Quick Action. Strange! 
• So set up the Quick Actions for Change Owner, Change Status and Close, and add them to the List View buttons. 

Service Setup

Modify your app to include Service setup if you are using any of the other service features. If it's straight cases, just use the regular setup. 

Email-to-Case

There is a new guided flow for Email to Case Setup which is really nice. 

See this Trailhead trail https://trailhead.salesforce.com/modules/service_lex/units/service_lex_channels 

Contact Roles

Aaagh! No Contact Roles! Well, it's OK, I created my own custom object related list last time because of some stupid limitation.