What about wi-fi?
Does your office have a wi-fi network that your phone could connect to instead? Our house has marginal 3g coverage but solid wi-fi, so I usually just switch that on when I get home. Faster speed, stronger signal, less need for the phone to search for data.
Also, when my Ally's original battery was old and not holding charge as well, I got into the habit of connecting it to a charger at my desk in the afternoons when I knew I'd be stationary for an hour or two. That would usually kick it from the 30% it'd hit by then back up to 70%, which was good enough to get to bedtime. Chargers are cheap, even direct from Verizon. However, I did finally replace the battery, and that plus a new optimized ROM made a world of difference.
