Did you update your PRL (Preferred Roaming List)? Go to the phone app and open the preferences via top left menu. Then scroll down and update the PRL, see what happens. Hopefully that helps.
When I swapped to the Pre I got better reception virtually everywhere. Hope the PRL update works for you.
Note for Sprint users: every Sprint device uses a PRL. Call tech support and request one. The IVR will do it but only rarely.
Get an Airave. Reception issues are a common problem for Pre indoors.
I found that the Pre more accurately displays the signal. My Treo 755p would always tell me I had 4 bars and then drop a call. Same thing with the iPhone.
another thing to try is to stop syncing Google Calendar, if that's what you're doing. A friend of mine had terrible reception on his Pre at home and when he stopped syncing google calendar, everything was fixed. I've seen many cases of this on Google, it looks like it's fairly common.
I've only noticed this at work. On the Centro I had at least 2 bars and could always get calls, but have problems with txt msgs. Now on the Pre I get no bars and once in a while 1 bar, I know it is because we are in a windowless cave in the middle of the building, lol. So far everywhere else has been okay.