I was logging into google voice again, and found myself in a familiar world. I send a text message, and when the person replies it's in my inbox AND my phone. The problem is, I have one of those crappy phones so I have to constantly be deleting messages because I run up to the limit.
Here's my thoughts, if you get a text message in Google Voice AND you're logged in, it gives the text message say 1 minute to sit in the inbox doing nothing, if you immediately respond INSIDE google voice, it doesn't bother sending it to your phone, additionally you could add a "send to phone" option for a text, then it will still send it to your phone in the event you're getting directions and you won't have internet access when you leave your computer.
Well there you are just one more idea.