As you say, nwg, you're riding different kinds of bikes on different sources (and with many more hills!) than we are. A 28-mile ride for me on a good day is just around two hours, with only gentle climbs. DH did 30 miles in the same time (while I took a break in the middle), so really not that long a ride on road bikes. We had a great tailwind on the way out so were able to maintain a pretty brisk pace. Coming back with a headwind (not too strong but noticeable) was a bit slower, but still faster than on your fatties.
So glad you're able to ride again, and that you're letting discomfort guide how long you should ride while rebuilding. My DH's crash was much less serious than yours, and he has healed up really fast. I'm so relieved about that as I'd initially thought he might be out of commission for weeks. He gets pretty cranky when he can't ride, so I wasn't looking forward to that!
Riding keeps him sane.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow