I agree with upther, City ID doesn't seem to drain battery but it can drain your wallet if you buy it. Just let it run until the trial expires then opt out. It won't run after that. You can dig around and find similar apps, but all of the one's in the market will not work because verizon's current CDMA technology doesn't allow concurrent data and voice so no caller id or city id on a voice call. City ID just cross references a database which get's updated (for the fee) and they have a patent which blocks other app from doing the same thing.
I also leave GPS on all the time and can confirm it only turns on when you are running an app that needs GPS and is off all other times. As for Wifi I mostly only go back and forth from work and home and have wifi at both places so I just leave wifi on as well and works fine for me. I don't use bluetooth so I leave it off.
When you're setting up for the first time verizon's backup assistant is already loaded on the device and asks to set it up. It is unnecessary as it's just redundant if you are syncing with your google account anyway. I wouldn't activate it. I also don't use any of HTC's social networking apps: flickr, twitter, facebook, friendstream (which uses htc's twitter and facebook app). I find the apps made by the services work better. That goes for Gmail as well, I use the android gmail client instead of HTC. Though the android gmail probably drains the battery more as you can set sync intervals with the HTC app, but I like the instant notifications of android gmail.
As far as the weather app, HTC's looks nice but it's actually kind of limited so I don't use it. I prefer weather channel's app and don't use a widget. If I want to see the weather I just click on it so it only updates when I need it.