If you are like me, you get bad signal and data reception in your house. I found the default Wi-Fi options a little annoying because the device turns off Wi-Fi in certain states to conserve power.
The following registry edit will keep Wi-Fi enabled even when it's in a suspended state.
HKLM\System\CurrentControlSet\Control\Power\State\ Suspend\
HKLM\System\CurrentControlSet\Control\Power\State\ Resuming\
HKLM\System\CurrentControlSet\Control\Power\State\ Unattended\
In all three areas, the {98C5250D-C29A-4985-AE5F-AFE5367E5006} key represents Power-manageable NDIS miniports (including Wi-Fi), so this is the value you'll want to change.
The default value is dword: 4 (i.e. Suspend). You'll want to change this to dword: 1 (i.e. UserIdle) to keep the wireless from shutting down during a suspended state.
You can find some additional info on the power states
here.
One thing to note is that the Wi-Fi isn't automatically on. All this change does is KEEP it on if it's already on (even if you lock/suspend the device). You can still turn Wi-Fi on/off using the Wi-Fi button or CommManager.
So why use this edit?
The obvious downside is that battery life is going to be shorter since we are keeping the Wi-Fi on during states where it would normally be off to conserve power. Basically, if you know you won't be using the Wi-Fi for a long period of time, it would benefit you to turn it off.
There are a couple of upsides that in my situation make this a desirable edit. The first is that I don't need to wait for my phone to connect to Wi-Fi. While the phone already has an "Always On" option, it still disconnects (and then reconnects) when you lock the phone. With this reg edit, it just stays on so there is no waiting for a reconnect. Also, I can still use the button to turn it on/off as normal. Basically, it behaves more like you would expect it to behave.
The other reason I like this reg edit is because of the low signal strength in my house. By default, the phone keeps flipping from 1x to EV. I understand this constant searching/switching already depletes battery life (and also keeps popping up that annoying Power Vision message). I understand one "fix" for the problem is to just force 1x mode, but that just seems like I'm gimping my phone.
More importanly, I've also read that 1x data transmissions send voice calls to voice mails, so if your e-mail/weather/news updates frequently (like mine does) then you run the risk of losing calls to voicemails. Since Wi-Fi trumps 1x and EVDO, this shouldn't continue to be a concern if the Wi-Fi connection is always active.