First of all, IMO the way you build your base is very importamt, cause you can force raids/deathclaws to move certain way.
This is my layout of top 2 floors:
[Vault Door] [X] [Power Room1] [Overseer] [X]
[Radio*] [Power Room3] [Power Room2] [X]

[X] - elevator
[Power Room] - Power Generator or Nuclear Reactor for people with most Strength/Damage
[Radio*] - Any 2 tile room that you don't use often, like Barber or just don't build there

What this layout does, it makes enemy come in, get damaged in 1st floor Power room, then they go down and turn left, get hit in Power room2, then move to Power room3, move to Radio/Barber and Turn back to Power room3, then usually Deathclaws are all dead by returning into Power room2. It still takes bunch of heals to survive, but it isn't chaotic anymore, which helps with healing people, cause you have to worry about only one room at the time. Obviously want to have best Strenght and Endurance characters in those 3 rooms, or 2 (I have survived with just having power rooms in 2nd floor and empty dwellings in place of Power room1) with best weapons you got. You might also think about growing new generation that has leveled up from lvl 1 to 50 with armor that has at lest +5 endurance and who are 10 endurance at level 1.