At PIT, jetway use depends on where you park and who you work for. Transstates' ERJ's and some of PSA's CRJ's, along with any DO-328's, DASH-8's, J-41's and the not-to-often unlucky Mesa CRJ have to use the ramp/stairs scenario. The other half of PSA's CRJ's and all of Mesa's and Chatauqua's ERJ's use the jetways, unless a gate conflict occurs. PIT was in the process of converting/fixing all of the jetways in the A concourse to operate with the regional jets, but it seems that the process ceased abruptly right after the status change announcement.
Honestly, I have seen CO at PIT hook up their jetway to a B-1900D before, so maybe it depends on how good the jetway mechanics are at a particular station.
If you are a hub or a "focus city", jetways should be your number one priority. Weather considerations aside, the safety issue of having passengers in a SIDA area where they could either get hurt or do something stupid or heinous can be greatly lessened or eliminated with jetway use.
Now, if only you could use the jetway power and air on an RJ in PIT......that would be something!