Tasker and the Secure Settings plug-in can help with this. For example, I have my phone set up so that if I am on my home WiFi network or if my Smartwatch is connected, it won't ask me for my PIN. Of course, when neither are connected, it will then require a PIN to unlock it.
As a practical matter, this means that nearly any time I want to use my phone, I don't have to unlock it, but if anyone outside my house were to try to use it, it would be locked. In this way, the security doesn't become a nuisance and lead to it not being used. The best part, at least on the Galaxy S4 and the older Galaxy Tab 10.1, you do not have to be rooted to do this.
For those unfamiliar with Tasker, it can be intimidating. It is definitely geared towards those who are willing to spend some time learning it and learning to think like a programmer at least a little. Not much more than basic logic, but I feel obliged to make that announcement.
Now, let's walk through how to do this so that when you're connected to a particular WiFi router you won't have to put in your password.
To start, purchase and install both Tasker and the free Secure Settings plug-in.
Next, open up Tasker and click on the profile tab. Then click on the "+" in the lower right. Then, choose State.
Next, choose Net and then WiFi Connected. This tells Tasker that you want to create a profile that will run whenever you connect to a particular WiFi.
On the next screen, I would recommend filling in the the SSID line with the SSID of the WiFi network you use. For example, if the name of your office WiFi is "LawFirm", you would put in LawFirm. Case counts. If you leave it blank, then this will run any time your WiFi connects, even if it is just some open WiFi network.
Next, hit the left arrow at the top. This step, for me at least, was not entirely intuitive.
Next, a little popup will ask you what task you want to do. Click on "New Task +", and you can just hit the check mark instead of giving the task a name.
On the Task Edit screen, click on the the "+" at the bottom. This time, choose Plugin and "Secure Settings".
On the Action Edit screen, click on the pencil next to Configuration. Choose "Dev Admin Actions". Then choose "Password/Pin".
On the next screen, check the Device Admin Enabled box. Then save this setting by clicking on the save or diskette button near the top.
This takes you back to the Tasker Action Edit screen. Click on the left arrow as before in the top left to get out of the action edit screen. Do it again to get back to the profile screen. Now, when your phone connects to the WiFi network you listed, it will no longer require you to put in the password (Note, you might have to turn your WiFi on and then off to get it to take effect, and there is sometimes a small lag time).
Of course, you will want the password to come back when you leave the WiFi network. To do this, on the WiFi Connected profile you created, tap and hold on the Secure Settings Clear Password after the green arrow. This will bring up a popup where you can choose to "Add Exit Task".
Again, choose to add a new task, click the check mark, and add a new task. As before, you will be adding a plugin and secure settings. Click on the pencil next to Configuration, then Dev Admin Actions, and Password/Pin.
This time, click on the "Disabled" button. Choose either the Password or Pin Code radio button and put in the password or pin you want to use. Save, and back out to the profile. On your profile you should have both a green arrow pointing right and a red arrow pointing left for your WiFi Connected profile.
Now, whenever you connect to your WiFi network, your phone will stop asking for a password, and when you disconnect, it will start asking for a password again.