I don't get this whole "They don't pay their fare share" BS...I've flown Part 121 since 2007, and during my furlough I flew Part 91 corporate, so I've seen both sides of the coin.
Part 121, at Horizon we fly into a good number of airports where GA is the dominant traffic (Such as STS, EAT, PUW, LWS)...and they don't get in our way. Occasionally we run into situations where we have to wait for someone to close an IFR plan to start down on the approach, but I can't honestly remember the last time that happened. Fact of the matter is, it's pretty rare that I (as an airline pilot) encounter GA aircraft. The whole "they're using our airspace, causing delays, etc" is BS.
As a GA aircraft "owner" (the 310) and a corporate pilot, I can tell you we paid our share of taxes. Have you taken the time to see how much gas is for GA aircraft? Have you taken the time to see the breakdown of taxes that are on each gallon of 100LL? If you fly your GA aircraft into an airport that is predominately Part 121, guess what...you pay landing fees, ramp fees and get raped on fuel cost...but it's a cost of doing business should you choose to fly in there. Currently 100LL is taxed at 19.4 cents/gal.