Had my first experience with Greyhound last December and I'd try it again. If you're considering it don't read the google reviews as they are overwhelmingly negative and filled with horror stories about lost and damaged packages. The positive ones often mention the obvious "intelligent shipper" tips like pack it to survive a nuclear holocaust and double label every box.

I had a pick up radiator support travel from New Mexico to PA during Christmas peak travel. Maybe 8 days end to end and changed buses at least 4 or 5 times that I know of and arrived with only a small tear in the box. The cost was about 1/2 of FedEx Freight but there are trade offs. One being that it's bus station to bus station only unless you want to pay extra for door to door which entirely kills the cost saving. Not every station in the network handles packages and sometimes the nearest one is 200 miles away.

The online tracking system is pretty horrible. My best guess is that it only updates when the box changes buses and then only if the baggage handler remembers to scan it. It clearly doesn't update every time the bus its on enters / leaves a station - ya know, like UPS trucks do. With my shipment they failed to scan it when it got to destination station and the bums at the station wouldn't answer their phone. The customer service rep managed to get through and in the end it was all good.